The structure of proteins: two hydrogen-bonded helical configurations of the polypeptide chain (co-author H. R. BRANSON); Atomic coordinates and structure factors for two helical configurations of polypeptide chains; The structure of synthetic polypeptides; The pleated sheet, a new layer configuration of polypeptide chains; The structure of feather rachis keratin; The structure of hair, muscle, and related proteins; The structure of fibrous proteins of the collagen-gelatin group; The polypeptide-chain configuration in hemoglobin and other globular proteins. Eight papers in a single offprint from: Proceedings of the National Academy of Sciences, Vol. 27, Nos, 4, 5, April, May 1951. [With:] Fundamental dimensions of polypeptide chains; Stable

THE STRUCTURE OF PROTEINS - NOBEL PRIZE IN CHEMISTRY 1954. First edition, very rare offprints, signed by Pauling. "In April of 1951, readers who turned the pages of PNAS were treated to a surprise: seven studies from the same authors, published back-to-back, all on the subject of protein structure . Grouping the papers together for maximum attention, authors Linus Pauling and Robert Corey must have realized the bombshell they had dropped on the scientific world. Knowledge of the inner workings of proteins - molecules often referred to as the building blocks of life - would be the key to understanding biology at the molecular level" (Christen Brownlee, The Protein Papers, 2012). "Protein research was one of the major areas of study in x-ray crystallography and biochemistry, with British x-ray crystallographers such as John Desmond Bernal, Dorothy Hodgkin, and William Astbury among the pioneers in the field. While visiting Oxford in 1948 and confined with the flu, Pauling started building protein models, constructing a three-dimensional model of keratin as a spiral molecular structure using paper, ruler, and pencil to sketch out a chain of amino acids, and drawing the atomic-bond lengths and angles from memory. He realized, however, that an x-ray pattern produced from his model would not match the x-ray patterns that Astbury had published. After his return to Caltech, Pauling set to work with Herman Branson and Robert Corey to come up with an accurate model. In 1950 he and Corey published two structures for keratin, using hydrogen bonding for a coiled peptide chain. Their ?-helix model had 3.7 amino acid residues per turn and called for a diffraction pattern showing about 5.4 angstroms between each turn, not quite on target with Astbury's value of 5.1 angstroms. The fiber manufacturing firm of Courtaulds in London soon confirmed the ?-helix in its commercial synthesis of artificial fiber similar to natural keratin, as did Perutz in later studies of natural keratin in the form of horsehair. In May 1951 Pauling and his coworkers published seven papers on protein structures in one issue of the Proceedings of the National Academy of Sciences (PNAS), including the ?-helix, parallel and antiparallel pleated sheets, and a winding three-helix model for the protein collagen" (DSB). "A decade before the structures of entire proteins were first revealed by x-ray crystallography, Linus Pauling and Robert Corey of the California Institute of Technology deduced the two main structural features of proteins: the ?-helix and ?-sheet, now known to form the backbones of tens of thousands of proteins. Their deductions, triumphs in building models of large molecules based on features of smaller molecules, were published in a series of eight articles, communicated to PNAS in February and March 1951. Their work had a significance for proteins comparable to that 2 years later of the Watson-Crick paper for DNA, which adopted the Pauling-Corey model-building approach" (Eisenberg). "New Scientist magazine once characterized Pauling as one of 'the 20 greatest scientists of all time, on a par with Newton, Darwin, and Einstein.' Pauling has also been called one of the two greatest scientists of the 20th century (the other being Einstein) and the greatest chemist since Antoine-Laurent Lavoisier, the 18th-century founder of modern chemistry" (American Chemical Society). Pauling is the only person in history to win two unshared Nobel Prizes - the 1954 chemistry prize "for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances", and the Nobel Peace Prize in 1962. This offprint was issued first in brown printed wrappers and somewhat later, presumably because the supply of these was exhausted, in cheaper white printed wrappers as here. The text is identical in both. "As Pauling was learning more and more about the structures of relatively simple molecules, in the mid-1930s, it occurred to him.…