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775 [1232] GRANIT
UHLENBECK [1234]
[1221]. This two-carbon compound com bined with the four-carbon oxaloacetic acid (one of Szent-Gyorgyi’s four-carbon compounds) to form the six-carbon cit ric acid. The citric acid underwent a series of changes that converted it to oxaloacetic acid once more. In the process of those changes it lost carbon dioxide and gave up hydrogen atoms that combined (through a series of complicated steps) with atmospheric oxygen. It was the combination of hydrogen and oxygen that yielded energy for the body. Once the citric acid had been con verted back to oxaloacetic acid, the latter was ready to take up another two-carbon fragment and go through the procedure once more. At each turn of this Krebs cycle one two-carbon compound was ground up into carbon dioxide and water.
The Krebs cycle has turned out to be the major energy producer in living or ganisms (though, of course, not the only one). Fat molecules are broken down into the same two-carbon compound into which carbohydrate molecules are bro ken down, so that the Krebs cycle repre sents the final stage of energy production from fats, too. When protein is con sumed for energy purposes, fragments enter the Krebs cycle at various stages, most but not all entering at the two-car bon compound stage. For his work Krebs shared the 1953 Nobel Prize in physiology and medicine with Lipmann. He was knighted in 1958. [1232] GRANIT, Ragnar Arthur Finnish-Swedish physiologist Born: Helsinki, Finland, October 30, 1900 At the time of Granit’s birth, Finland was part of the Russian empire, but in 1918 it had gained the status of an inde pendent nation. Granit earned his medical degree at the University of Helsinki in 1927. After several years in the United States, where he met Hartline [1276] and Wald [1318], and in Great Britain, where he studied under Sherrington [881], Granit moved to Sweden, permanently, in 1940. Like Hartline, Granit worked on indi vidual nerve cells of the retina of the eye and was the first to show that single nerve fibers could distinguish between different wavelengths of light. He shared, with Hartline and Wald, the 1967 Nobel Prize in medicine and physiology. [1233] KUHN, Richard (koon) Austrian-German chemist Born: Vienna, Austria, December 3, 1900
Died: Heidelberg, Germany, July 31, 1967 Kuhn, after serving in the Austro- Hungarian army in World War I, studied at the University of Vienna, then Mu nich, and obtained his Ph.D at the latter institution in 1922 under the direction of Willstatter [1009], In 1929 he received a professorial appointment at the Univer sity of Heidelberg. The direction of his later research was much like that of Karrer [1131]. Kuhn and his group synthesized both vitamin A and vitamin B2 almost simultaneously with Karrer. He was one of the first, in 1938, to isolate vitamin B6 (pyridoxine) in pure form, beginning with 14,000 gal lons of skim milk. In 1938, a year after Karrer’s Nobel award, Kuhn too received the Nobel Prize in chemistry. Hitler, offended by a Nobel Peace award to Carl von Os- sietzky, a man in a Nazi concentration camp, refused to allow Germans to ac cept such awards. Kuhn was forced to reject the prize and it was only after World War II that he could be properly honored.
[1234] UHLENBECK, George Eugene (oo'len-bek) Dutch-American physicist
Djakarta, Indonesia), December 6, 1900 Uhlenbeck, born in what was then part of the colonial empire of the Neth erlands, was educated in the homeland, obtaining his Ph.D. in 1927 at the Uni versity of Leiden. He then went to the 776
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United States. He joined the faculty of the University of Michigan in 1927, then, during World War II, worked on radar research at the Massachusetts In stitute of Technology. In 1961 he went to the Rockefeller Institute (now Rocke feller University) in New York City. It was while he was still a student at Leiden that he made his most notable contribution. Soon after Pauli [1228] had demonstrated the necessity of a fourth quantum number to describe the electrons in a given atom completely, Uhlenbeck and his colleague Goudsmit [1255] demonstrated that it could be in terpreted neatly in terms of particle spin. They showed furthermore that the unit of electron spin was half a common quantum unit so that the electron may be said to have a spin of + Vi or —Vi. Eventually, similar spins (equal to Vi or some multiple thereof) were found to exist for almost all other particles. [1235] DUBOS, René Jules (dyoo-bohs') French-American microbiologist
February 21, 1901 Dubos received his early education (in agricultural sciences) in France. He ar rived in America in 1924 and obtained his doctorate three years later from Rutgers University in New Brunswick, New Jersey (Waksman [1128] was teaching microbiology there). Dubos’s doctoral thesis dealt with soil microor ganisms and that remained his field of research thereafter. Upon receiving his degree Dubos joined the Rockefeller Institute for Med ical Research (now Rockefeller Univer sity) in New York and in 1938 became an American citizen. Like Waksman, Dubos was interested in the antibacterial substances produced by microorganisms. In 1939 he isolated such a substance from Bacillus brevis and named it tyrothricin. This was found to be a mix ture of several polypeptides (with mole cules consisting, like proteins, of chains of amino acids, but only of compara tively short chains). Dubos’s compounds were not very effective in themselves but their discov ery aroused interest in Fleming’s [1077] penicillin and led Waksman to isolate streptomycin and other men to produce the broad-spectrum tetracyclines of the late 1950s. [1236] PAULING, Linus Carl American chemist
ary 28, 1901 Pauling, the son of a druggist, grew in terested in chemistry at the age of thir teen, thanks to a friend with a home chemistry laboratory. He attended Ore gon State College, graduating in 1922. He obtained his Ph.D. in 1925 at the California Institute of Technology and remained there throughout his academic career, becoming a professor in 1927. In 1926 he went to Europe for a year and a half to study under Sommerfeld [976]. Before he was thirty, Pauling had rev olutionized thinking concerning the structure of molecules. Lewis [1037], Pauling’s long-time friend, had intro duced Ernest Rutherford’s [996] nuclear atom into the chemical structure of mol ecules, but to do so he had pictured a static atom, with motionless electrons placed at the corners of a cube. Mean while, though, De Broglie [1157] had revealed the wave characteristics of par ticles and it was necessary to view elec trons as wave forms without fixed posi tions. London [1226] had then pioneered this view in connection with the hydro gen molecule. Pauling began with De Broglie’s quan tum mechanics and worked out a theory whereby electrons, as wave forms, in teracted in pairs to form a stabler and less energetic system in combination than either had been separately. This combi nation could only take place if the atoms, of which the electrons formed part, remained in close proximity. To separate the atoms, one had to add en ergy to break the electron combination. In this way the chemical bond between atoms was accounted for and Kekulé’s [680] system of depicting molecules was rationalized. But Pauling’s picture was clearer than 777
[1236] PAULING
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Kekulé’s, for Pauling could show that a particular bond might have some charge separation associated with it. A bond could therefore be partially ionic, thus restoring a bit of Berzelius [425]. Much that had been mysterious in organic chemistry and had been accepted simply as empirical fact, could now be shown to malfs sense in Pauling’s more elaborate view.
Pauling further showed that certain compounds were stabilized by the in teraction of electrons over systems of bonds that were alternately double and single. The electron waves were, so to speak, “smeared out” over a relatively extended region. This theory of “reso nance” explained the unusual properties of benzenes, accounted for Gomberg’s [950] free radicals, and performed many other tasks that could not be touched without it. In 1939 Pauling published his views in a book entitled The Nature of the Chem ical Bond, which he dedicated to Lewis. It proved to be one of the most influen tial chemical texts of the twentieth cen tury.
Pauling went on to apply his notions of molecular structure to the complex molecules of living tissue. He was one of the first to advance the suggestion, in the early 1950s, that protein molecules were arranged in helices (that is, in spiral staircase form); a similar structure ad vanced soon afterward by Crick [1406] and James Dewey Watson [1480] in con nection with nucleic acids was to prove a thunderous breakthrough in the field of genetics. (Pauling might have antici pated Crick and Watson, had he had bet ter X-ray diffraction data available to him.) At that time Pauling also studied cer tain blood diseases and worked out use ful theories as to the structures of abnor mal hemoglobin, thus introducing the notion of a molecular disease, one caused by the abnormal structure of, in this case, a protein molecule. In 1954 Pauling was awarded the Nobel Prize in chemistry for his work on molecular structure. After World War II Pauling was in the forefront of the fight against the nuclear danger overshadowing the world. He vig orously fought nuclear testing by the United States and the Soviet Union alike, being quite certain that the very survival of civilization and even of life depends on nuclear disarmament. For this he was awarded the 1962 Nobel Peace Prize, making him the second per son in history (after Marie Curie) to win two Nobel Prizes. In 1970 Pauling made another sort of headline with his contention that large doses of vitamin C were effective in the prevention of the common cold. [1237] MENZEL, Donald Howard American astronomer
11, 1901 Died: December 14, 1976 Menzel graduated from the University of Denver in 1920 and gained his Ph.D. at Princeton in 1924. From 1932 Menzel served on the Harvard faculty and from 1954 to 1966 was director of the Har vard Observatory. In his later years he took up the thankless task of combating one of the most popular of the pseudo-scientific fal lacies that periodically afflict mankind; that of “flying saucers” or “unidentified flying objects” (UFO’s). Combating the enthusiastic proponents of the theory that flying saucers represent dangerous (or beneficent) invasions from outer space, Menzel, with the assistance of Mrs. Lyle Gifford Boyd, published an urbane analysis of the various reports that effectively demolished them. In retirement Menzel was given the task of supervising the assignment of names to the lunar features discovered on the other side of the moon (and on our side) by the probes that have circled our satellite and landed upon it. [1238] HINTON, Christopher Hinton, Baron
English nuclear engineer Born: Tisbury, Wiltshire, May 12, 1901
778 [1239] DU VIGNEAUD ELVEHJEM [1240]
Hinton, the son of a schoolmaster, spent his teenage years as an engineer with a railway. He attended Cambridge University on a scholarship and gradu ated in 1926. During World War II he worked with chemical explosives. Thanks to the work of Szilard [1208] and Fermi [1243], nuclear explosives had been developed in the United States and Hinton was placed in charge of a project designed to harness uranium fission to peaceful purposes. In this, Hin ton was successful. The Soviet Union had built a small nuclear station for the production of electric power in 1954, but the world’s first large-scale station of this sort was Calder Hall, built under Hin ton’s guidance. Calder Hall was put into action in 1956 and Hinton was knighted in 1957 and created a life peer in 1965. He took the title of Baron Hinton of Bankside. [1239] DU VIGNEAUD, Vincent (dyoo- veen'yoh) American biochemist
1901
Died: Scarsdale, New York, De cember 11, 1978 Du Vigneaud graduated from the Uni versity of Illinois in 1923 and obtained his Ph.D. at the University of Rochester in 1927. After some time at Illinois with Rose [1114], he accepted a professorial position at George Washington Univer sity School of Medicine in Washington, D.C., transferring to Cornell University Medical College in New York City in 1938.
Du Vigneaud’s interest lay chiefly in the amino acids and, of his numerous achievements, three stand out. In the late 1930s his studies of the amino acid methionine and of related compounds made it possible to trace how the body shifted a methyl group (—CH3) from compound to compound. By such shifts, the body sometimes com pletes the construction of a complicated molecule, slipping in the last carbon atom, so to speak, by way of the active methyl group of the methionine mole cule.
In 1940 Du Vigneaud identified a compound called biotin as being what had earlier been referred to as vitamin H. Working on tiny quantities of biotin with the sure instinct of the chemical de tective, Du Vigneaud deduced its rather complicated two-ring structure in 1942. Chemists at Merck Laboratories synthe sized the compound in 1943, according to Du Vigneaud’s specifications, and it turned out to be biotin indeed. Most exciting of all, however, was his work on the hormones produced by the posterior lobe of the pituitary gland. For years he had been working on one called oxytocin. He had broken it down into fragments, studied those fragments, and deduced that oxytocin was a small pro tein molecule made up of only eight amino acids. (The average protein mole cule contains several hundred amino acids.)
By 1953 Du Vigneaud had even worked out the exact order in which the amino acids appeared in the chain, as Sanger [1426] was doing for the much more complicated molecule of insulin. The simplicity of oxytocin made it pos sible for Du Vigneaud to go beyond Sanger’s work, for in 1954 he put to gether the eight amino acids in the order he had deduced and found that he did have oxytocin with all the properties of the natural material. It was the first pro tein hormone ever synthesized and pointed the way to similar victories over more complicated proteins. For this deed Du Vigneaud was awarded the 1955 Nobel Prize in chemistry. [1240] ELVEHJEM, Conrad Arnold (el'veh-yem) American biochemist Born: McFarland, Wisconsin, May 27, 1901 Died: Madison, Wisconsin, July 27, 1962 Elvehjem, the son of a farmer, spent his professional life at the Univer sity of Wisconsin. He was educated there, graduating in 1923 and obtaining 779
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his doctorate in 1927. He joined the fac ulty in 1925, was head of the biochem istry department in 1944, dean of the graduate school in 1946, and president of the university in 1958. In the 1930s Elvehjem’s interest turned to the vitamins, a subject occupy ing much biochemical attention in that decade. The molecular structure of the vitamins was yielding to chemical analy sis and so was the molecular structure of the coenzymes. Men like Euler-Chelpin [1011] and Warburg [1089] had shown that Harden’s [947] coenzyme and closely related coenzymes contained nico tinic acid as part of the molecular struc ture. Funk [1093] had, as long ago as 1912, isolated nicotinic acid from rice polishings. He, however, had tried its effect on beriberi and failed. Yet its proved occurrence in a mole cule as vital to the body’s workings as a coenzyme now restored interest in it. Since Funk’s finding, it had been amply proved, thanks to the work of Gold berger [1027], that pellagra too was a dietary-deficiency disease. Funk himself had suggested that pellagra might be such a disease. Would nicotinic acid help there?
In 1937 Elvehjem, working with dogs suffering from blacktongue, the canine analogue of pellagra, administered 30 milligrams of nicotinic acid to one. Im provement was phenomenal and further doses brought on complete recovery. This was more than a matter of simply proving that nicotinic acid was a vitamin and an antipellagra factor. Biochemical knowledge had reached the point where one could now say that pellagra was a set of symptoms that arose from the fail ure of certain enzymes to function nor mally. The particular enzymes that failed were those that made use of coenzymes containing nicotinic acid as part of the structure. The body could not manufac ture nicotinic acid from simpler com pounds and had to have it supplied, ready-made, in the diet. In this way the rationale of vitamin re quirements was worked out. Since then, many of the B vitamins have been con nected with specific coenzymes; for in stance, pantothenic acid was shown to be a portion of Lipmann’s [1221] coenzyme A, and riboflavin (vitamin B2) was shown by Theorell [1267] to form part of other coenzymes. Elvehjem’s later work was on trace minerals, like zinc and cobalt, a field of research that was to reach a climax a decade later with the work of Folkers [1312]. Such minerals are also essential to life in small quantities and, like the vitamins, perform their functions as component parts of enzymes. [1241] LAWRENCE, Ernest Orlando American physicist
gust 8, 1901 Died: Palo Alto, California, Au gust 27, 1958 Lawrence, the son of an educator and the grandson of a Norwegian immigrant, was educated at the University of South Dakota, graduating in 1922. He was not a particularly good student outside sci ence and his early ambition was to enter medicine. A physics teacher at the Uni versity of Minnesota roused Lawrence’s interest in that field, however. He went on to obtain his Ph.D. in physics from Yale in 1925 and joined its faculty. In 1928 he transferred to the University of California, and he remained there, be coming full professor in 1930. One of the big problems in the nuclear physics of the 1920s was improving methods of bombarding atomic nuclei. At first the only available projectiles were the alpha particles used by Ernest Rutherford [996]. These, however, had a double positive charge and approached the positively charged atomic nucleus only with difficulty. In 1928 Gamow [1278] had suggested that protons be used instead. These were hydrogen ions, which were very easily available, and they could be imparted the necessary energies by being accelerated in an elec tric field. Since they possessed only a sin gle positive charge, they would be less strongly repelled by the atomic nuclei they approached than alpha particles would be. Various devices for imparting the ac- Download 17.33 Mb. Do'stlaringiz bilan baham: 
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