Chapter 21 17 triple helix-1

Pauling point Surprisingly, Pauling seemed capable of navigating political ups and downs without significantly affecting his science.In 1951 and 1952 alone, he officially published 43 articles, including research papers, popular science sketches, notes, and academic reviews.Among them are a series of epoch-making papers on protein structure, as well as articles on the following basic topics: basic phosphorus bond structure and aerobic acid structure, borides and lead alloys of transition elements, resonance of hydrogen molecules and metals The nature of compounds, etc.He also showed that water molecules can coalesce into beautiful lattices around a gas atom, taking hydrate chemistry a big step forward.He reviewed the structural chemistry of molybdenum and at the same time began work on a new theory of ferromagnetism.At Caltech, he had reformed the doctoral exam, and his thoughts on the issue were published in the press.In addition, he began work on a new textbook, the greatly revised Second Edition of General Chemistry.In the popular journal Science Digest, he explained to readers why "it pays to be familiar with science."

Awards and accolades came one after another.He was elected vice-president of the prestigious American Philosophical Society, which had become an intellectual club founded by Benjamin Franklin, and he became the first recipient of the Lewis Medal awarded by the Berkeley chapter of the American Chemical Society .He was appointed to a study group of a Presidential Commission tasked with studying the needs of the nation's health.His portrait was included in the "Half-Century Hall of Fame" by "Popular Mechanics".Add to this a long list of various honors and titles.He even became an unwitting movie star, appearing in a Frank Capra film for Caltech's admissions service that put him through the director's rigor.

Back home, everything was pleasant, at least in Pauling's eyes.His family's home, Medel Hill, is often the place where the chemistry department gathers to celebrate the start of a new academic year.Pauling hosted such gatherings on the lawn in front of his home.Food is simple and drinks are plentiful.On one occasion, someone recalls, punch was served, served in a rocket cone.Pauling and Eva entertained throngs of party guests, most of whom were Pauling colleagues or visiting scholars.Sometimes Eva holds tea parties at home for the employees' wives.She didn't get on well with most of them--to her, they were disheveled and vulgar; her guests thought her sharp-tongued, politically pompous, and intolerant of others' opinions.Eva is more interested in the monthly folk dance evenings.In the years after she and Pauling returned from their visits to England, these dancers were often invited to her home.Eva has always loved music.Moving the furniture against the walls and turning on the tape recorder, she could dance with these friends and children for hours on end—on one occasion, in the heat of the moment, she fell and injured her wrist. fracture.

Folk art became a hobby of hers.She chose all the clothes for her husband, so Pauling's clothing began to reveal his unique style. In the early 1950s, Pauling's well-tailored suits and ties often gave way to casual clothes and sweatshirts, and even the office shirts were flamboyant, printed in bold and expansive patterns.At this time, Pauling, with long gray hair that is gradually thinning on his head, with strands of hair coiling around his head, looks a bit like Einstein.As he got older, his personal style added something new: a pair of half-rimmed Franklin spectacles over his eyes, which were pushed up to his forehead when he was talking, and peeked at the material on the tabletop to illustrate certain When he made an argument, he lowered his glasses to the tip of his nose again.Sometimes, he wears a beret.In the 1950s, when gray suits were popular, all this added to his image of a liberal rebel.Pauling is very casual with himself and doesn't care what others think of him, so he feels very comfortable with his attire.

As for his children, it seems that their careers are also thriving.The first child, Linus Jr., is a resident doctor in the psychiatry department of a hospital in Honolulu. He decided to take his wife to settle in Hawaii. One reason is that the local has a paradise-like pleasant climate, and the other reason is that he hopes not to be too close to his parents.At this time, Pauling already had the third generation, and the eldest grandson Linus III was born in 1948.Due to the distance, Pauling and Eva seldom visit their children and grandchildren. Peter made up for his older brother's lack of distance from his parents.Following his father's example, he entered Caltech for graduate studies, specializing in physics and chemistry.This made Pauling proud, but Peter's siblings worried about his ability to follow in his father's footsteps.Everything seemed to be going well for Peter, with a passing grade in his studies.On the other hand, he too, like the typical college student, has developed a penchant for beer and parties.He befriended some of Pauling's graduate students and postdocs. Around 1950, a small social scene began to emerge at the Pauling residence.On a warm afternoon, five or six young future scientists climbed up the hill together, went to Pauling's house to drink beer, jumped into the swimming pool for a while, and joked with Peter.At the same time, it was a good opportunity to tease and tease slim blonde teenage Linda Pauling.

Linda was very happy to receive the attention of these young people.In addition to the usual reasons, this is also an opportunity to achieve psychological balance. Recently, she has increasingly felt that her family does not take her seriously.Linda has always loved her father very much, and always tries to draw his attention to her.She had wanted to be a good and desirable daughter of her father, obedient and respectful, polite, quiet and lovely.However, apart from being mechanically stroked by him on the head, she got nothing more from her father.Pauling's attention, in order of importance, was entirely on scientific research, Eva Helen, and politics, with Linda at best fourth.In order to win her father's favor, she worked hard to develop her interest in science in prep school; when she was 18 years old, she worked in a laboratory at Caltech in the summer, testing alloys with X-rays; I hope to enter the chemistry department of the university for further study.Very good, Pauling said.Linda even grew jealous of Eva Helen's frequent opportunities to travel with Pauling, and the way her father hoped for her mother's approval or asked her advice.Linda will never forget how she waltzed into Pauling's study one afternoon, circling, to show her father an outfit she thought was particularly beautiful.Pauling glanced at her quickly out of the corner of his eye and said, "You know how beautiful this dress would be on your mother," and he turned back to continue his work. calculated.

But Linda was now beginning to receive the glowing attention from her father's students, and she was delighted in her heart for it.When Pauling and Eva weren't at home, Peter and Linda would have formal get-togethers with their poolside mates, sometimes small, sometimes boisterous. Even with Pauling present, these young guests, some his students, some postdoctoral researchers, were hardly affected by their taste for such gatherings.They are the few students who have been strictly selected and have the right to enter this private residence.Of course, there was plenty of fun by the pool, and opportunities to join Pauling in his octagonal study to discuss scientific research.Sometimes, when Pauling needs to stretch his body after theoretical research, he will walk across the grass, pick a place to sit down, and with his trademark smile on his face, he will start chatting with these young people and discuss science. , politics and their future.A brief poolside conversation can completely change the course of a person's life.Matt Messelson is one of them. One summer in 1952, he went swimming in the mountains.He was a friend of Peter, a very talented young man who had previously attended Caltech, spent a year in graduate school at Berkeley, and was now considering transferring to the University of Chicago.On this day, Pauling, wearing a suit and tie, walked into the hot yard, leaned over and crawled by the swimming pool, splashed the water with his hands, looked directly at the young man, and asked, "Hey, Matt, what are you doing next school year?" What's the plan?" Messelson said he was going to Chicago. "But, Matt," said Pauling, "that's insincere. Why don't you come to the Polytechnic Institute as my graduate student?" By the swimming pool, the eyes of the world-renowned scientist gazed at him, admirably. .Messelson looked up at Pauling and said, "Okay, I am very willing." In this way, he finished his studies under Pauling's guidance, and later went to Harvard University to continue studying molecular biology and obtained an outstanding degree. Achievement.Just like this, a great man showed his face for a while, bursting out with sparks of wisdom, and then he got into his residence again, leaving the group of young people to continue laughing and playing.This is an event packaged in the style of a Southern California pool party: a group of young people, full of pride and talent, gather together to talk about the past, the present, the sea and the sky, and talk about science without restraint. The words are so generous and the scenes are so breathtaking. The excitement is really unimaginable.One recalled that Pauling's residence was often a "steamy place."

Pauling is a professor who is loved by students.Most people regard him as a spiritual leader. He practiced and pondered in the mountains, received divine revelation, and then communicated the divine truth to the masses.He gave lectures to first-year students, and he had begun to take on a legendary color.Here and there he would throw in some surprising tricks—he could use a 5-inch slide rule to the sixth decimal place, while asking some skeptical first graders to use a hand-cranked computer to verify that he got As a result (he was right every time)—the students seemed to genuinely enjoy the brilliant ideas that flowed from his head for the world's greatest chemist.Listening to Pauling's lectures, "it was like being in a beautiful concert," recalled one audience member.

These students came to see Pauling as their role model.One of the secrets of becoming another Pauling is recognizing what people call a "Pauling point," "the point at which things have reached a point where the right answer can be found -- at which point, if one step forward, Or go a step further, then the situation will become more complicated, and even the answer will become more elusive," Martin Capras explained.Capras, a professor at Harvard University, was one of those young men sitting by the Pauling family's swimming pool. "The essence of Pauling's point is to judge the situation and seek the correct answer." This important skill can only be truly mastered by a brilliant master. When dealing with difficult problems, it is not necessary to clean every dead corner.It's a dashing and timeless way to approach science.Most people find this almost impossible to imitate.

When dealing with students and postdoctoral researchers, Pauling never takes the approach of guarding them.He does not advocate prescribing every step for them, or even pointing them in a specific direction—"In such an environment, a person either sinks to the bottom of the water, or swims independently to the other side," said a student Recalling—however, as Pauling's reputation grew, his few encounters with students gradually became colored by the traditional sermons of Buddhist masters.Alexander Rich had recently obtained a master's degree. He went to work in Pauling's laboratory, hoping to try to do some scientific research, but he couldn't decide on a specific project: he first did research on sickle cells, and later on Jump to the theoretical topic of carbon bond connection at once.Nothing could excite his imagination.He was very anxious, not sure what to do. One night in 1950, he walked into Pauling's study, and the two talked about general scientific issues without touching on specific content.At this time, Pauling took out a book that someone had just sent him.It was the proceedings of a meeting of the Royal Society on quantum chemistry, and there was nothing in it except the theoretical calculations that Rich had been working on.Pauling flipped through the book and threw it away. "Worthless," he said, "a load of crap." Rich asked why, and he replied, "Well, I was chasing after the thirties to find the exact solution to these equations I can't solve it. Since then, people have used various approximations to try to solve one problem after another. Approximation methods emerge in endlessly, which is no different from whipping a dead horse ’” That day, Rich didn’t realize Pauling was talking about his future until after driving down the hill. "Since Linus can't solve these problems," he said to himself, "why do I think I can do better than him?" It was this side-talk that led Rich to decide to delve into X-ray crystallography.It was this change in professional direction that created the conditions for his outstanding achievements in this area at MIT.

Messelson compares Pauling's style to Socrates' famous saying: Virtue cannot be taught in words, but it can be taught by example. "I think that's Linus' style of influencing people." In the early 1950s, among the young people who were particularly appreciated around Pauling, many of them later made their mark in science.These people gathered around Pauling and were deeply influenced by Pauling.Counting from the first batch of students under Pauling in the early 1930s, these people have the closest relationship with Pauling. The Mystery of Life (continued) Pauling is delighted to be able to act as a father figure to young and promising scientists.However, the greatest joy of his life is always to engage in scientific research. After 1951, Pauling began to apply his research results on protein to the structure of other long-chain biomolecules, including starch and nucleic acid.These components are certainly not as important as proteins in terms of human function, however, their structure seems to be simpler, so it may be relatively easier to solve the problem with the help of his modeling method. In the summer of 1951, Pauling began to delve into materials related to deoxyribose nucleic acid, and often found people to discuss.Everyone now calls this component DNA, the most common form of nucleic acid in chromosomes.Astbury had done some X-ray studies of smears in the 1930s, showing that DNA is a long-chain molecule with a repeating structure.This could also be a helix, but it only has 4 subunits.This secondary unit is called a nucleotide.These nucleotides seem to be found in the DNA of all animals, and the number of each nucleotide is almost equal, which is different from the 20 or so amino acids of proteins, and their content in various molecules is very different Yes, each nucleotide is made up of ribose sugar, phosphate, and a different base.There are four types of bases: adenine, guanine, thymine, and cytosine.When Pauling conducted resonance research in the early 1930s, one of the topics was to theoretically summarize the structure of guanine; this structure has the shape of a flat plate, and the shapes of the other three bases seem to be the same.The key to studying DNA is to figure out how each base is connected with ribose and phosphate to form nucleotides, and then how these nucleotides are connected into long chains.Pauling thought that figuring this out would not be too difficult compared to the structure of proteins. In either case, this is not the most pressing issue. DNA is by weight an important component of chromosomes, but so is protein.Most scholars believe that the protein part most likely contains genetic information.Proteins come in a variety of forms and functions, as well as a wide variety of secondary structures, so that their complexity can hide genetic traits.Relatively speaking, DNA seems to be relatively simple. It is probably only a structural component that is only used to help chromosomes fold and open.Biddle thought so, and so did Pauling.At the beginning of 1952, almost all important genetics scholars held this view. The only evidence to the contrary comes from a rather obscure paper published in 1944 by the Rockefeller Institute scholar Oswald Alfred.Alfred found that the DNA itself could apparently pass new genetic traits between pneumococci.However, for many years, no one paid attention to Alfred's work.Pauling knew about the structure—he had come into contact with Alfred during World War II when he was working on man-made antibiotics for pneumococcal antigens—but didn't think it mattered. "I was aware of the thesis that DNA is a genetic material," Pauling said, "but I didn't accept it. You know, I was working on proteins at the time, and I thought proteins were most likely the genetic material , it cannot be nucleic acid—of course, nucleic acid also plays a role. In my writings on nucleic acid, I always mentioned the concept of nucleoprotein. At that time, I thought more about protein than nucleic acid.” Gerald Oster is from Brooklyn Pollet, who is a visiting professor at Caltech. In the summer of 1951, Pauling talked with him about his research work. At that time, the structure of DNA was only an interesting topic of modeling technology.Oster had done some research on the effect of moisture on DNA. After he returned to the eastern United States, he sent Pauling some data obtained in his research.At the end of one of the letters, a point of opinion occurred to him. "I would like you to write to Professor J. T. Rundle, Strand Kings College, London," he wrote. "His friend, Dr. Wilkins, once told me that he had several very clear fiber diagrams for nucleic acids." Clear graphics of DNA are difficult to obtain.Take a random piece of hair and you can x-ray the clear pattern of keratin, but the DNA needs to be separated from the nucleus, and once it is separated from the proteins that are stuck together, this process is very difficult. .Back then, techniques for isolating DNA generally disrupted the molecule to some degree, and the end product would be the sodium salt of DAN, which stands for sodium deoxyribonucleic acid.But how does the molecular structure change during separation?There are still people who are puzzled that even purified sodium deoxyribose is very difficult to use for X-ray diffraction.At that time, the first few X-ray images obtained by Astberry in the 1930s, as well as a new photograph he published in 1947 to illustrate his new insights into the structure of DNA, were available in the published literature. all the information on .However, these data are of little value.X-ray patterns from globulins provided too messy data for successful analysis, while Astberry's DNA photographs provided too little data.Pauling could get some rough idea of ​​the size and magnitude of the cyclical segments in these graphs, but the graphs were not clear enough to generalize more information from them. Pauling needed clearer X-rays, so he planned to write to Wilkins.It should be said that it is rare for a scholar to actively participate in the research of a certain project, obtain some original data, and hand it over to others before publishing it in some form.But Oster tried to convince Pauling that Wilkins had no intention of doing much with the photographs in his possession, which Auster believed had been taken for a long time.So, one day in the late summer of 1951, Pauling took the opportunity to write to Rundle's laboratory, asking if he could take a look at the materials preserved by Wilkins. After reading Pauling's letter, Wilkins couldn't make up his mind what to do. Wilkins is a thin, bespectacled physicist who has yet to achieve much in his career.A year before this, he had gained quite a lot in one thing: he had found a method that could be used to take the clearest X-ray pictures in the world.This was discovered by accident when he was studying sodium deoxyribonucleic acid solution.This substance, when dissolved in water, forms a viscous solution.Wilkins found that by carefully dipping the end of a glass rod into the solution and then pulling it up slowly, the substance was pulled into fine fibers like spider silk.Those very long strands of DNA apparently lined up along the fibers.Wilkins remembered that Bernal had found that globulins took clearer pictures when they were in a wet state, so he placed an X-ray camera in a place with high humidity and took pictures of the pulled fibers. X-ray photos, the results are many times clearer than the graphics taken by Astberry.There are a lot of bright spots in the photo.This result of Wilkins can be used immediately to confirm the conclusion that DNA has a cyclic and ordered crystal structure, so its mysteries can be unraveled. However, he alone cannot solve this problem.Wilkins was a man of many talents—he began his scientific career by contributing to the separation of uranium isotopes for the Manhattan Project—but he was not well trained to read inter-optical photographs Moreover, at Kings College, due to the lack of equipment for studying X-ray pictures, his work was also affected.Therefore, in 1950, he decided not to publish the photos he took, hoping to have the opportunity in the future.Then analyze the relevant data thoroughly, and use better equipment to retake this type of photo.In this way, things were put on hold, and Auster interpreted this as a lack of interest in Wilkins.In fact, during this time, Wilkins has been planning to build better experimental facilities, and hopes to get help from relevant parties. By January 1951, Wilkins had acquired new equipment and found someone who could use it. She was the talented young crystallographer Rosalind Franklin.Franklin made a name for himself with his meticulous X-ray studies of difficult-to-study coal products.Sadly, the relationship between Wilkins and Franklin was rocky from the start.Believing that Franklin had been hired to assist him, Wilkins immediately gave her his X-rays and his interfiber studio, and assigned one of his graduate students to She is an assistant.But, on Franklin's side, she thought she was being hired to carry out independent research work.When they received Pauling's letter, the two had already fallen out, and they couldn't figure out how to conduct DNA research for a while, so it was even more difficult to answer Pauling's request.At this time, Franklin himself took higher-quality X-ray photos, and carried out research on the DNA structure as the owner of the photos.Wilkins was also interested in studying this structure—he wanted Franklin's help.Wilkins knew in his heart that if he sent the photo to Pauling, both he and Franklin might be defeated by Pauling.He began to notice that DNA might be a helix, and Pauling had already used this form of structure to put the British in an embarrassing situation. Therefore, the more Wilkins thought about it, the more worried he became.For a whole week, he picked up and put down Pauling's letter, thinking silently whether there was any other way to deal with it.In the end, he took up his pen and wrote back, saying that he was very sorry, and he wanted to take a closer look at the information he kept before he could release these X-ray photos. Pauling was not discouraged, and he wrote to Wilkins's boss, Rondel, to make the same request.Unable to help, Rundle wrote back: "Wilkins and others are too busy trying to figure out how to read DNA x-rays. Both in terms of their research and the efforts of our entire laboratory , I’m afraid it’s inappropriate to hand over these photos to you.” This is already August.Pauling put the DNA issue down.By November, the Journal of the American Chemical Society published an article on the structure of DNA by a man named Edward Langwin.Pauling immediately saw that the results of this article were wrong.According to Pauling, the phosphoric acid in the DNA molecule should have one phosphorus atom surrounded by four oxygen atoms forming a tetrahedron, which means that each phosphorus is connected to five oxygen atoms.Pauling had just reviewed the chemical properties of phosphorus for a paper.In his view, Langwin's model was the result of a complete fabrication.He wrote a letter to the Journal of the American Chemical Society about this.As it turned out, Pauling was right. More importantly, it made Pauling think about how DNA is constructed.Langwin placed the phosphorus in the center of the molecule, with the corresponding planar bases extending around.It's entirely possible -- Astberry's X-rays don't rule out such an arrangement -- and it helps resolve an important problem: the four bases of DNA come in two sizes. , that is, two bicyclic purines and two smaller monocyclic pyrimidines.For example, this is a spiral, and Astberry's photographs have shown that this may be a structure.If you manage to arrange bases of different sizes on the inside of a long helical molecule, there are problems of how to assemble and stack.With the bases facing outward, it is easier to visualize the model of the molecule.This is similar to the situation of protein helical molecules. It is easier to obtain the alpha helix model by letting the side chains of each amino acid be placed outwards in the center of the helix. Pauling imagined that if the bases were facing outward, then the inner core of the helix should be piled up with phosphoric acid.of.Phosphoric acid gathers in the middle and the bases face outward.This is consistent with the X-ray data.After reading Langwin's paper, in Pauling's mind, the problem of DNA structure has been transformed into a problem of how to stack phosphoric acid together. When Pauling put down the DNA problem again and returned to protein research, the situation described above was the level he had reached. In the autumn of 1951 he received an invitation to attend a special meeting of the Royal Society dedicated to the many questions British scholars had raised about the structure he envisioned.The date was set on May 1, 1952. Pauling wanted very much to attend this meeting. For several months in late 1951 and early 1952, he had been making preparations for the conference.He and Corey experimented, modified, and rethought their proposed structures, especially those of muscle protein and collagen.One aspect of the problem with myosin was that the X-rays from it were rarely clear, so Pauling did it himself and dried two hundred swatches.Most of these photos were taken using mussels as experimental samples from Caltech's marine farm in Corona del Maire.Based on his new photographs, he concluded that the majority of muscle protein is made up of alpha helices, with about 10 percent of what looks odd on x-rays; Then find out what it is.As for collagen, Corey prepared a 20-page document for internal circulation, which proved to be the triple helix structure proposed by the two of them.Corey also redoubled his efforts to storm the structure of lysozyme in several stages, and he hoped he would be the first to determine the complete structure of the globulin.On this issue, Pauling's laboratory once again competed with Prague's research group. Corey's opponents were Perutz and Kendrew, who were doing the same thing with hemoglobin and myoglobin at this time. Work. Back in January 1952, Pauling began to make specific arrangements for his trip to Europe in the spring.During this trip, in addition to attending the May meeting of the Royal Society, he also went to the University of Toulouse in France to receive the title of honorary doctor, and visited several Spanish universities along the way.He submitted an application for the extension of his passport to the relevant parties. Then, once again, a disturbing thing happened. Mrs. Shipley On Valentine's Day 1952, Mrs. Ruth Shipley, Director of the State Department's Passport Division, sent Pauling a note. "Dear Dr. Pauling: You are hereby informed that your request for a passport has been seriously considered. However, the government will not issue you a passport because, in our opinion, your proposed travel does not qualify for U.S. best interests." After Pauling read the note, he was annoyed, but not surprised.Passports have been another politically used weapon since the passage of the Internal Security Act in 1950, which gave the government the power to deny dissidents' requests to travel abroad.Shipley, the younger sister of Hoover's former FBI director, was a fanatical anti-communist and security-conscious about everything.She often uses her position as head of the State Department's passport division to take advantage of anyone she and the State Department's security services -- the FBI with which she has close ties -- suspect are walking too far or shouting too loudly Refuse to issue passports to them. After 1950, Shipley's power to refuse passports was almost unfettered.She can wield her new weapon with impunity like a determined Cold War warrior.In just one year after May 1951, her office banned more than three hundred Americans from traveling abroad, sometimes without even giving the slightest reason.Its targets are wide-ranging, ranging from Paul Robertson, an African-American singer and self-confessed pro-communist, to Salvador Lurian, a virology expert at Indiana University and a moderate leftist. Otherwise, the lack of a visa to enter the United States puts the organizers of international conferences, including the International Chemistry Congress, in an embarrassing position.Pauling had publicly protested against visa denials and joined a group formed to protest the Internal Security Act.However, the turmoil he encountered with the passport issue this time was particularly difficult to deal with, because he could not even find a channel to appeal. Shipley has been watching Pauling will take what kind of action.She became even more resolute when she saw Pauling's name on the list of those who had publicly denounced her policies. In late October 1951, in response to Pauling's earlier request for a passport for a trip to Europe and India, Shipley proposed a special investigation by the State Department's Office of Security.The investigation time is not long, and the goal is clear.State Department officials reviewed relevant FBI files and interviewed an unnamed individual who learned that Pauling was "an intellectual utopian reformer" who became politically active at the behest of his wife ; while his wife is "completely a political ignorant", she "must convince her husband at all times that he is one of the three greatest thinkers in the world today. , he should be obliged to assume the responsibility of leadership and show his ability." Based on this information, Shipley determined that "there was sufficient reason to believe that Dr. Pauling was a Communist" and therefore refused to issue him a passport.Responding angrily to the passport refusal that occurred on Valentine's Day, Pauling sent a letter to Truman asking him to "correct this practice and urge the relevant parties to issue me my passport. I am a loyal Conscious American citizens have never engaged in activities that are detrimental to national interests or violate discipline.”He also enclosed a copy of the military medal certificate that Truman had previously issued to him.In his reply, the secretary of the president stated that this was purely a decision of the passport office, and the White House had asked for a review.However, Shipley remained unwavering, and Truman's office never expressed anything. In April, to make things easier, Pauling decided to confine his travels to England, and wrote a polite letter to Shipley accordingly.The letter asked if he could have an interview with her at her convenience, given that he would be on a business trip to the Eastern United States later that month.He also humbly mentioned in the letter that the purpose of going to Washington was to chair a meeting of the Office of Naval Research.He then hired Abraham Lincoln Welling to act as counsel in his case.威林和鲍林先后向护照处寄去了就业资格审查委员会关于鲍林的听证会书面记录、俄国人攻击鲍林的书面材料以及他得到的许多奖状的复印件。 但是，希普利的决心已定。4月18日，她再次书面通知鲍林，他的护照不能颁发。 时间已经非常紧迫。英国皇家学会会议定于5月1日举行。4月21日，鲍林和爱娃亲自上访护照处。他们在会客室等了片刻，然后有人将他们领到了露丝·希普利面前。希普利举止僵硬，双唇紧闭。鲍林夫妇心想，她是一位公仆，因而对其彬彬有礼，当然，言辞中也不失坚定。他们要求希普利说明不发护照的原因。鲍林后来回忆时说，她的回答是有关他进行共产党领导的活动的“一个相当含糊空泛的一般结论”。她干脆不让来访者继续询问，明确示意拒发护照的决定是她权限内的事，决定是她亲自作出的，争论下去将毫无意义。然后，她将两人领到了安全和领事事务科科长办公室。这位科长要求鲍林提供能表明自己不是共产党人的书面证据。鲍林请人连夜从帕萨迪纳航空邮寄有关的文件资料，第二天就将这些文件送去了。在这些文件中，有一份就是声明自己不是共产党员的宣誓书。结果，对方冷冰冰地对他说，他们会尽快作出决定。至于到底在什么时间，则无可奉告。 此时，鲍林已经完全绝望，真是欺人太甚！他以受人尊敬的公民身份亲自前来解决问题，但是有人竟敢像对逃学成性的顽童一样对他无礼。 他再次调整了自己的出访计划，打算改乘晚些时候的一次飞机航班。另一方面，他又继续进行抗议活动。他甚至设法让国家科学院院长写了一信。然而，这一切仍无济于事。4月28日，能将他送到伦敦的最后一次航班离起飞只剩两个小时了，他收到了最终决定，他的护照不予签发。鲍林第二次致电英国皇家学会，说明他已无法出席以他的名义将要召开的那次会议。 发起召开这次会议的英国人简直不敢相信这是事实。大多数与会者曾在一次正式的茶话会上得知，鲍林将于会议开始前一天到达。有一位与会者在后来回忆时说：“大家都非常震惊，美国国务院以危险人物为名阻挠这位伟人参加会议，真是愚蠢之极，令人气愤。” 当这一消息传开时，科里和理工学院晶体学家休斯已经抵达伦敦。科里内定在会上作他自己的一次报告。鲍林曾关照过休斯作好思想准备，代替他在会上进行活动，但是，这竟然真的发生了，实在令人啼笑皆非。在蛋白质结构研究的历史上，这终究是最为重要的报告之一，鲍林当然应当亲自到场发言。休斯事先没有听到任何消息，因此直接去希思机场迎接鲍林可能搭乘的最后一次班机。他眼巴巴地望着飞机舷梯，至终都未见导师踪影，这下才开始当起真来，看来只得由他代作报告了。那夜，他在下榻的旅馆房间里，临时抱佛脚，反复阅读鲍林事先准备的手稿，上面有二十多处注明需要用计算尺核对的数据。这是一份长篇讲演稿，休斯反复演练，希望能保证正好用完会议限定的时间。 第二天上午，休斯怀着兴奋紧张的心情，踏进了皇家学会庄严华丽的会议厅。他走上主席台，此时才得知，他发言的时间是20分钟。“我站在那里，面对皇家学会的听众，身后上方挂着查理二世的油画，头脑里还在思考到底将报告中哪些内容删去，”他说。科里首先报告，论题与氨基酸有关；与此同时，休斯则紧张地在发言稿上东画西划，砍去一行行的字句。轮到他作报告时，还未来得及编辑整理。这样，他只能提纲挚领地回顾鲍林研究结构的化学方法——肽基的平面性状所显示的重要意义，原子之间的距离和键角的正确数据，氢键结构的最大化——此时，预定时间已到。一位听众注意到讲演的准备工作非常糟糕，提议让休斯的讲演延长10分钟时间，这才让他有机会读了鲍林的最后结论：“鉴于这一研究方法至今已经取得成功，我们似乎有理由相信有人为多肽链设想的结构，与目前已经证实的某些结构原理相距太远，……因而可以排除在我们考虑的范围之外。”要是鲍林在场朗读这些字句，他的声音中一定会显示出慷慨激昂的自信。休斯坐了下来，如释重负地松了一口气。会场上响起了一些零星的掌声。 那天，在接下来的时间里，休斯记得：“这些英国人坐在那里，对我们说这也不是，那也不是。”阿斯特贝里率先发难，提醒大家说，阿尔法螺旋无法解释5.1埃的反射现象，而他本人提出的扭曲缎带模型能够做到这一点；鲍林计算的密度“误差太大，因而是不合理的”；鲍林忽视了测链的相互作用；过分依赖于从人造多肽中测得的数据，等等。多萝西·霍奇金则持中立的态度，她在报告中称，她所得到的胰岛素衍射图既不能支持阿斯特贝里的模型，也无法说明鲍林方法的正确性。伯纳尔重申尚无充足的证据说明任何球蛋白中存在阿尔法螺旋。伊安·麦克阿瑟指出，鲍林在作数据计算时，对别人的批评意见采取了不以为然的态度，并且提到，“有时候，阿尔法螺旋既可以用于对误差的解释，又可以用作对事实的说明。'怖拉格则可以免开尊口了。 最后荣幸地赢得发言机会的是研究血红蛋白的美国学者约翰·埃德塞尔，只有他为鲍林作了辩解。他称赞鲍林的化学方法是“在我们为蛋白质多肽链的可能结构进行思考的过程中一个重要的里程碑”，他还将阿尔法螺旋称为“蛋白质化学领域中具有伟大的创造性思维成果之一”。 但是，还是产生了无可挽回的影响。休斯感到，加州理工学院的小组已经成为众矢之的。特别是在那一天结束时，他和科里都急于批驳这些英国人的批评意见，但只被允许用5分钟时间。“我十分生气，”休斯回忆道。“我写信告诉鲍林，我感到我们上当受骗了。” 布拉格也感到有些后悔。会议一结束，他就致函鲍林称，与会者对鲍林的缺席感到遗憾。“大家对您提出的阿尔法螺旋进行了热烈的讨论，有些人对您的模型仍表示怀疑，要是您亲自在场，就可直接回答他们的问题了。”至于他本人，布拉格补充说，他相信阿尔法螺旋“在本质上是正确的”——至少在人工多肽的情况下是这样。 尽管鲍林关于蛋白质的思想在英国受到了冷遇，但大家对他在护照问题上受到的刁难都表示同情和不满。首先，在5月11日的会议上，美国国务院科学顾问乔·科普夫里本人就受到一群怒气冲冲的英国科学家的围攻，他们同声谴责了美国政府的旅游政策，认为这与俄国人的政策没有什么两样，是不得人心的。英国的左翼报纸大肆宣扬了这一事件，伦敦《工人日报》的醒目标题是“笼罩着科学家的铁幕”。 5月5日，美国国务卿艾奇逊读到了一份刊登在那天上午出版的伦敦《时报》上一封来信的电传稿，作者名为罗伯特·鲁滨逊爵士。他是英国重要的有机化学家，诺贝尔奖金获得者。在一般人的心目中，鲁滨逊是一位言辞谨慎的人，但是，他在鲍林事件上，严厉斥责美国国务院的“蛮横”行为。“要是假装事先根本不知道美国当局为什么要采取这种严厉行动的原因，那就是自欺欺人，”他写道，“但是，这并不等于说我们对此就可以置身事外而不感到震惊。”美国驻伦敦使馆的一位官员在一封旨在辩护的照会中强调：“这一事件不可避免地会严重损害美国的利益。” 来自法国的消息也同样糟糕。英国皇家学会会议结束后两天，法国人将鲍林选为定于夏天召开的生物化学讨论会“名誉主席”，这是对美国政府的当头一棒。法国科学家异口同声地谴责鲍林事件；一位生理学家对美国驻巴黎的科学专员称，美国人一定是“神经失常了”。鲍林事件成了左翼《人道报》上头版横幅大标题。该报还报道了法国科学家想进入美国签证受阻的情况。“这类事件日积月累，惹人反感。许多人对我们的动机表现出严重怀疑，”这位专员在给他的华盛顿上司的信中这样写道。 在《纽约时报》的办公室里也听到了来自欧洲的强烈抗议。5月上旬，该报发表了两篇新闻报道，并且配上了一篇社论，题为“鲍林博士的两难处境'：。这篇社论要求对政府的护照政策进行反思。同时鲍林的抗议信件犹如雪片一样飞向国务院。伯纳尔以及来自芝加哥大学的几位重要的原子科学家也写了一封抗议信，责问国务聊艾奇逊：“鲍林教授到英国去，有何害处？他会带去什么情报？他会在那里说什么坏话？即使他有这个胆量，与那些误导人的广告所带来的破坏相比，又算得了什么，以致这个堂堂大国非要阻碍它最杰出的公民之一出国旅行不可？”爱因斯坦也致函艾奇逊提出了抗议，随后又给鲍林寄去了他个人表示支持的便函。“您为争取旅行权而进行的斗争将功不可没，”他这样写道。“像您这样一位独立思考的人，同时受到美国官方和俄国官方的无理对待，这是一件意味深长的事，在某种程度上也是一件滑稽可笑的事。”甚至杜布里奇对此也无法保持沉默了，他公开宣布鲍林事件是“与我们的民主传统格格不入的”。 接到公民投诉的还不只是国务院。有五六名美国参议员和众议员，其中包括亨利·卡博特·洛奇和理查德·尼克松，读了所在选区选民的愤怒信件和电报后也深有触动，他们要求有关方面澄清这一事件。 至于鲍林，他在各方面的支持下，又重新抖擞精神投入了战斗。一方面，他又寄去了一份要求颁发护照的申请，他打算在那年夏天去英国和法国旅行；另一方面，他对报界发表谈话——他曾对一位记者说：“恕我直言，这一事件自始至终都是一桩丑闻。”他向艾奇逊和杜鲁门写了抗议信，同时还将此事告到了俄勒冈州一位见解独特的参议员韦尼·莫斯那里。据鲍林回忆说，莫斯也被“激怒”了，他在参议院会议上咆哮如雷，痛斥国务院的护照政策是“暴政”，艾奇逊是“一个令人厌恶的政客”。接着他又开始起草新的法律条文，使人在不满意有关方面在护照问题上作出的决定时，有一条上诉的渠道。全国报纸和思想类杂志都对这个问题展开了讨论。 尽管发生了这么多情况，希普利却仍置若罔闻。她要议员们去读一读众议院非美活动调查委员会编写的小册子——《解除美国武装和打败美国的一场运动》，其中详细地描述了鲍林参与共产党阵线活动的情况，企图以此来堵住众人的口。一位科学家接通了她的电话，责问为什么拒发鲍林的护照，她毫不客气地斩断了他的话，说：“我在科学问题上必须听从科学家的意见，因为他们是专家，同样，在拒发护照这么一个技术问题上，科学家也必须服从护照处的决定。” 然而，国务卿艾奇逊可不能采取回避的态度，他想要为他的护照政策辩护。不过，他在研究了这一问题以后，开始认识到，决定是否撤销一个人的护照，并不存在清楚的标准，而且也没有适合的渠道让人申诉。5月下旬，鲍林事件促使国务院在公开场合第一次概括地说明了政府拒发护照的政策，但其使用的语言却非常抽象和含糊，招致新闻界强烈的不满。几个星期以后，艾奇逊发表了较长的一篇解释性文章，其中涉及到如何分步考虑申诉的详细说明，被拒发护照的人可以保留聘请律师帮助辩护的权利。该文措辞似乎给人以这样的印象，就是申诉的办法已经存在好几个月了。但是，这篇文章对鲍林来说完全是新闻，特别是说他还有聘用律师的权利。他立即致函艾奇逊，说他的解释“与我本人所受的对待怎么也挂不上钩”。 抗议的浪潮使人们尤为关注鲍林要求颁发护照的新申请将会有怎样的命运。6月，希普利像往常一样签字拒发。不过，在根据惯例上报艾奇逊办公室盖章批准时，后者要求重新予以审理。在接下来的一个星期里，国务院高层官员深入地议论了鲍林的案子，决定尽量避免把事情闹大，悄悄地结束这一公共关系方面的尴尬局面。于是，希普利的意见遭到否决，鲍林可以领到带有限制条件的护照——只能适用于在英国和法国的短期旅行——而且他还必须签署一份宣誓书，否认自己是共产党员。这事将不公之于众。如有记者问起，官方的口径是：“新的证据”使情况发生了变化，虽然艾奇逊参与了这一决策的过程，但是他的名字将不会出现在有关的任何文件中。除此之外的详细情况也不予提供。 鲍林听到这一消息时，感到非常吃惊，同时也非常兴奋。7月11日，他来到洛杉矶外事办公室，正式签署了宣誓书。7月14日，他领到了护照。 并非每个人都高兴。露丝·希普利因为自己的意见被否定而怒不可遏。胡佛长久以来一直对鲍林感兴趣，此时也被惊动了。他派一个特工找到希普利的办公室，询问“新的证据”是什么。希普利对这个人说，联邦调查局了解的情况与她一样多，然后关照胡佛的特工到国务院去仔细查一查有关鲍林的档案。这些特工经过详细透彻的研究后，得出结论说：“查阅档案并未发现所谓的新证据到底是什么，也许是指档案中大量的信件和评论，其内容全是对前一次拒绝给当事人颁发护照而提出的抗议。” 鲍林的心情又开始舒畅起来了。公众抗议促使政府改变护照的政策，他这个案子算是开了一个先例。希普利现在也有人管管了。要是一个人出国旅行的权利被剥夺，那么根据一项拟议中有关护照的新办法，当事人可以上诉，从而能确保听证会开得更加公平和公正。 杂耍演员 鲍林出人意料地来到巴黎出席国际生物化学大会，一时引起了轰动。他在政治上碰到了麻烦，但敢于与政府对抗，这些新闻使他在法国成了人们心目中的英雄。在匆忙之中为他临时安排的有关蛋白质结构的讲演，引来如潮的听众。讲演结束后，学者们将他团团围住，大家都急切希望能与这位名誉主席握一握手，同时还对他主张的原则表示由衷的钦佩。鲍林和爱娃在特里厄农下榻的房间里接待了川流不息的朋友和来表达良好祝愿的人们， 大会结束后一星期左右，鲍林又出席了国际噬菌体学术报告会。这次报告是在位于巴黎城郊的卢瓦蒙修道院里举行的。这个修道院已有几个世纪的历史。会上，鲍林听取了美国微生物学家阿尔弗雷德·希歇介绍的构思奇妙的试验，在场的人都谈了自己的看法。判定到底是蛋白质还是DNA充当了遗传的载体，希歇和他的同事马撒·切斯曾找到一种方法，只要使用各自分开的放射性记号，就可以标示某种类似细菌的病毒所具有的DNA和蛋白质。通过对这些记号的追踪，他们终于能令人信服地表明，蛋白质根本就不起作用，只有DNA控制着复制新病毒的过程。 奥斯瓦尔德·阿佛列的试验是作为一项探索性的研究提出的，引起的影响比较小。但是，上面这种所谓的“夹杂有搅拌器的试验”却能清楚地表明DNA是遗传性物质。这一试验之所以冠上了这样的名称，原因在于试验过程中使用了一种无疑是非技术性的器械。适合于病毒的结论也许同样适用于高级生命体。随着愈来愈多的人了解到希歇一切斯试验的结果，对生命复制现象感兴趣的研究噬菌体的学者，还有遗传学家和生物学家，开始将他们研究的重点从蛋白质转到了DNA上。鲍林也很快地意识到，自己已经走上错误的轨道。这倒不是说蛋白质不重要，蛋白质仍然是机体发挥功能的必不可少的成分，但是，现在已经非常清楚，产生遗传性状的主要分子是DNA，而且它还是控制蛋白质生成过程的一个因素。 对鲍林来说，认识到这一点有一个痛苦的过程，但是他很快就逾越了这一个障碍。他颇为自信，感到自己有能力解开DNA之谜。事实上，他已经开始思考这样一个问题，而且这个问题看来还非常简单。唯一的问题是，会不会有人抢在他前面取得胜果，但是，他不会把这一点真正放在心上。威尔金斯和富兰克林正在研究这一个问题——事实上，在5月份英国皇家学会会议结束以后，科里参观过富兰克林的实验室，看到过她拍摄到的一些精彩的Ｘ光照片——不过，尚无迹象表明，他们两位中有谁具有足够的化学基础，可以对鲍林形成严重的危胁。要是布拉格参与其中，那就另当别论了。但是，能够表明在卡文迪什有人正在考察DNA的唯一证据来自德尔布吕克的一位门生，他的名字叫詹姆士·沃森，22岁，正在做博士后研究工作。他曾写信给德尔布吕克，谈到了几个月前曾为DNA寻找模型之类的事。德尔布吕克曾把沃森的信向鲍林说过，这似乎并不是什么大不了的事，虽然在德尔布吕克的眼里，沃森是一个好学生，但因成绩还不够突出，因而他到加州理工学院当研究生的申请未被批准。况且，卡文迪什的这些先生至今尚未在任何竞赛中打败过鲍林。 在卢瓦蒙会议上，鲍林曾经与一些人谈起过可以用他解决阿尔法螺旋问题的方法研究DNA的结构：就像科里和他的同事们在研究氨基酸时用过的方法那样，用Ｘ光图片来证实DNA的模块结构。他说：首先弄清楚碱基的确切形式以及它们与糖和磷酸的关系；然后再构造出一个模型，它在化学上最可能是一种长链结构。 在卢瓦蒙会议上，沃森就是围聚在鲍林身边的人之一，他十分用心地听了鲍林的讲话。此时，他已经知道，鲍林的方法是解决DNA问题的正确途径，而且他已经设法采用这种方法。 沃森参加卢瓦蒙会议完全是出于礼仪，因为他是“噬菌体研究集团”的一员。这个集团是由加州理工学院德尔布吕克和印第安那大学卢里安两人手下的研究人员组成的一个松散团体。这些人认为，“裸露基因”是生命体剥去所有外表以后最终剩下的基本形式，除了复制以外别无其他功能，而噬菌体是与此最为接近的研究对象。形式越简单，就越容易研究。噬菌体研究集团的学者们相信，病毒是继摩尔根的果蝇和比德尔的霉菌之后，研究遗传性状的又一重要载体。 沃森比大多数人更早认识到，DNA是了解基因的关键。他在卢里安的指导下取得博士学位以后，争取到一份奖学金去欧洲研究微生物新陈代谢和核酸生物化学，但是他很快就感到厌倦了。于是，他东冲西撞，希望能找到灵感。1951年春天，他到拿不勒斯开会，总算如愿以偿，威尔金斯在会上出示了几张拍摄的Ｘ光照片。虽然沃森对Ｘ光衍射图并不内行，但他仍能认识到，威尔金斯的研究工作表明，DNA具有一种规律性的循环结构，可以形成纤维的形状用作Ｘ光研究。这就意味着DNA的结构问题是可以解决的——但要弄清楚这种结构，他还需要学习Ｘ光衍射的知识。他曾主动要求让他到威尔金斯的实验室工作，但因为他对该室正在从事的研究一无所知而被拒之门外。1951年秋天，在德尔布吕克的帮助下，他终于在卡文迪什与肯德鲁一起，学习如何对蛋白质进行Ｘ光衍射研究的方法。 有人认为，对于像沃森这样一种兴趣多变的人来讲，最高明的做法是尽量让他们得到别人的指导。因此，沃森被安排与佩鲁茨的一位研究生合用一间办公室。这个人的名字叫弗朗西·克里克，他对Ｘ光衍射技术的了解已经到了炉火纯青的地步。 两个人马上动手干了起来。他们可谓是天生的一对：克里克已经三十五六岁了，当研究生年龄是大了一些——战争耽误了他的学业——然而，他这个人充满自信，性情直爽，十分健谈，甚至有点啰唆，留着时髦的络腮胡子，爱穿三件一套的西服；至于沃森，年轻，瘦削，腼腆，下穿美国式网球鞋，上留小平头的发式。欧温·切加夫为他俩描绘了一幅用意尖刻的现代画：“一位已经35岁，面带一副赛马场票贩无可奈何的神色……经常喜欢用假声发音的人，在云山雾海的高谈阔论中，偶而也会闪现出一星半点智慧的火花。另一位则尚未见过世面，……露齿一笑，与其说是胆怯，不如说是狡黠，……一个其貌不扬的山野村夫。”他说，克里克和沃森看上去就像是一对“杂耍演员”。 但是，这两个人却相互钦慕。克里克不久就明白沃森为什么“在多数场合被人视为聪明过头了”。沃森在碰到克里克之后几个星期就写信给德尔布吕克，称克里克“无疑是与我一道工作过的最聪明的人，也是我看到过的研究方法与鲍林最为接近的人”。鉴于两人对鲍林这位帕萨迪纳怪杰都极为崇拜，因此上述言辞中的赞美之意也就非常明显了。沃森第一次感受到鲍林之魅力是在1949年夏，那时他在加州理工学院与德尔布吕克一起工作了几个月，同时还先后认识了鲍林实验室的几位年轻人。沃森只是在离鲍林很远的地方见过他一眼，但这已经足以给他留下了深刻印象。“世界上谁也比不上莱纳斯，”沃森后来写道。“即使他在胡吹乱编，那些着了迷般的学生也决不会看出什么破绽，因为他显示出来的自信可以折服任何人。”鲍林的地位独特，风格鲜明，他是一位科学巨匠。他还有一个和和美美的家庭，他总喜欢驾驶赛车风驰电掣般地四处兜风。对于年方19的沃森来说，鲍林是一位值得仿效的榜样。 克里克开始时并不是鲍林的崇拜者，他是鲍林的竞争对手。布拉格、佩鲁茨、肯德鲁等人在一起进行学术讨论时，他也在场。正是这些讨论引出了1950年关于蛋白质结构的那篇考虑欠周的论文。克里克和这些人一样，没有注意到平面肽链的重要作用，因此，在鲍林用阿尔法螺旋表明他们的理论漏洞百出的时候，他也承受了由此而来的屈辱。他从这次经历中，得到了三点难忘的收获。第一是鲍林的研究方法，就是根据对化学原理所掌握的坚实基础，借助于建模技术，就可对结果作出合理猜想，这是弄清楚巨型生物分子的最快途径。第二，不能光凭试验得到的一条证据就动摇自己对一种理论的认识——他亲自看到，鲍林果断地决定暂不理会5.1埃这一异常的反射现象。第三，螺旋就是需要寻找的形式。 沃森刚来时，克里克研究的一个项目已经达到了成熟的阶段，他已无必要再去没完没了地在数学上解释血红蛋白的衍射图式。沃森只花了几天功夫，就向克里克提供了他要寻找的东西——相对来说比较简单但从长远来看却更为重要的目标：DNA。两个人在研究方法上迅速地达成了共识：与其推导出复杂的数学模型，直接而又明确地解释Ｘ光的衍射结果，还不如借助化学常识构筑结构的一个模型。正如沃森所说，他们决定“仿效鲍林，并在他本人发起的这场竞赛中将他击败”。 克里克和沃森在1950年秋天第一次尝试解决DNA的结构问题，这方面的情况已有许多报道，其中记述最为引人入胜的当算沃森本人撰写的《双螺旋》一书。用一句话即可概括：他们的尝试时间不长，并且以失败告终。他们采用了鲍林的研究方法，花了几个星期设想了一个三螺旋模型。这三个螺旋相互缠绕，中心是磷酸。这一模型与密度数据似乎是吻合的，Ｘ射线数据与每一个分子中有两到四条链组成的情况相容，因此，这就解决了一个理论问题。如果DNA是遗传物质，那么它就会对机体传送某些具体的信息；因而就需要有一种语言，借助于某种方式将有关信息翻译为生成蛋白质的指令。当时，人们已经清楚，糖和磷酸是形成简单循环的组件，它们在DNA螺旋的方向上是不变的。碱基则是可变成分，碱基变了，但Ｘ光的图形显示出一种循环的晶体结构；螺旋的核心——结构中形成循环的部分——一定包含着循环的次级结构，也就是糖和磷酸，碱基向外伸展，就不会产生阻碍。换句话说，DNA与阿尔法螺旋相像。沃森和克里克的设想与鲍林的思路是很相像的。