Linus Paulingアメリカの科学者

Linus Pauling氏、完全なLinus Carl Pauling氏（1901年2月28日、米国オレゴン州ポートランド生まれ-1994年8月19日死去、カリフォルニア州ビッグサー）、アメリカの理論的な物理化学者であり、2人の非共有ノーベル賞を受賞した唯一の人物となった。彼の最優秀賞（1954年）は、化学結合の性質と分子構造の解明におけるその使用についての研究に対して授与されました。2番目（1962年）は、核兵器のテストを禁止する彼の努力を認めた。

初期の人生と教育

ポーリングは3人の子供のうちの最初の子供であり、薬剤師のハーマンポーリングと薬剤師の娘のルーシーイザベル（ダーリング）ポーリングの唯一の息子でした。オレゴン州コンドンとポートランドで初期の教育を受けた後、オレゴン州農業大学（現在はオレゴン州立大学）に通い、後に妻となるAva Helen Millerに出会い、化学工学の修士号を取得しました。その後、1922年に賞賛されました。その後、カリフォルニア工科大学（Caltech）に出席し、ロスコーG.ディキンソンがX線を使用して結晶の構造を決定する方法を示しました。彼は博士号を取得しました。 1925年に彼の結晶構造紙から得られた論文について。国立研究員としての短い期間の後、彼はグッゲンハイム研究員としてヨーロッパで量子力学を研究しました。彼は18か月のほとんどをドイツのミュンヘンにあるアーノルド・ソマーフェルトの理論物理学研究所で過ごしました。

Elucidation of molecular structures

After completing postdoctoral studies, Pauling returned to Caltech in 1927. There he began a long career of teaching and research. Analyzing chemical structure became the central theme of his scientific work. By using the technique of X-ray diffraction, he determined the three-dimensional arrangement of atoms in several important silicate and sulfide minerals. In 1930, during a trip to Germany, Pauling learned about electron diffraction, and upon his return to California he used this technique of scattering electrons from the nuclei of molecules to determine the structures of some important substances. This structural knowledge assisted him in developing an electronegativity scale in which he assigned a number representing a particular atom’s power of attracting electrons in a covalent bond.

To complement the experimental tool that X-ray analysis provided for exploring molecular structure, Pauling turned to quantum mechanics as a theoretical tool. For example, he used quantum mechanics to determine the equivalent strength in each of the four bonds surrounding the carbon atom. He developed a valence bond theory in which he proposed that a molecule could be described by an intermediate structure that was a resonance combination (or hybrid) of other structures. His book The Nature of the Chemical Bond, and the Structure of Molecules and Crystals (1939) provided a unified summary of his vision of structural chemistry.

The arrival of the geneticist Thomas Hunt Morgan at Caltech in the late 1920s stimulated Pauling’s interest in biological molecules, and by the mid-1930s he was performing successful magnetic studies on the protein hemoglobin. He developed further interests in protein and, together with biochemist Alfred Mirsky, Pauling published a paper in 1936 on general protein structure. In this work the authors explained that protein molecules naturally coiled into specific configurations but became “denatured” (uncoiled) and assumed some random form once certain weak bonds were broken.

On one of his trips to visit Mirsky in New York, Pauling met Karl Landsteiner, the discoverer of blood types, who became his guide into the field of immunochemistry. Pauling was fascinated by the specificity of antibody-antigen reactions, and he later developed a theory that accounted for this specificity through a unique folding of the antibody’s polypeptide chain. World War II interrupted this theoretical work, and Pauling’s focus shifted to more practical problems, including the preparation of an artificial substitute for blood serum useful to wounded soldiers and an oxygen detector useful in submarines and airplanes. J. Robert Oppenheimer asked Pauling to head the chemistry section of the Manhattan Project, but his suffering from glomerulonephritis (inflammation of the glomerular region of the kidney) prevented him from accepting this offer. For his outstanding services during the war, Pauling was later awarded the Presidential Medal for Merit.

While collaborating on a report about postwar American science, Pauling became interested in the study of sickle-cell anemia. He perceived that the sickling of cells noted in this disease might be caused by a genetic mutation in the globin portion of the blood cell’s hemoglobin. In 1949 he and his coworkers published a paper identifying the particular defect in hemoglobin’s structure that was responsible for sickle-cell anemia, which thereby made this disorder the first “molecular disease” to be discovered. At that time, Pauling’s article on the periodic law appeared in the 14th edition of Encyclopædia.

While serving as a visiting professor at the University of Oxford in 1948, Pauling returned to a problem that had intrigued him in the late 1930s—the three-dimensional structure of proteins. By folding a paper on which he had drawn a chain of linked amino acids, he discovered a cylindrical coil-like configuration, later called the alpha helix. The most significant aspect of Pauling’s structure was its determination of the number of amino acids per turn of the helix. During this same period he became interested in deoxyribonucleic acid (DNA), and early in 1953 he and protein crystallographer Robert Corey published their version of DNA’s structure, three strands twisted around each other in ropelike fashion. Shortly thereafter James Watson and Francis Crick published DNA’s correct structure, a double helix. Pauling’s efforts to modify his postulated structure had been hampered by poor X-ray photographs of DNA and by his lack of understanding of this molecule’s wet and dry forms. In 1952 he failed to visit Rosalind Franklin, working in Maurice Wilkins’s laboratory at King’s College, London, and consequently did not see her X-ray pictures of DNA. Frankin’s pictures proved to be the linchpin in allowing Watson and Crick to elucidate the actual structure. Nevertheless, Pauling was awarded the 1954 Nobel Prize for Chemistry “for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances.”