By mid century, scientists knew proteins were chains of amino acids. The next questions were how those chains fold and in what order the amino acids sit.
In 1951 Linus Pauling, Robert Corey and Herman Branson proposed the alpha helix. They used precise measurements of small molecules and the rule that the peptide bond is flat. Their model showed a chain coiling into a spiral, held together by hydrogen bonds between nearby backbone groups. The alpha helix proved to be one of the most common shapes in proteins.
In 1953 Vincent du Vigneaud and his team synthesized oxytocin, a natural peptide of nine amino acids. It was the first peptide hormone made in a laboratory. Du Vigneaud received the 1955 Nobel Prize in Chemistry, cited in part for this first synthesis of a polypeptide hormone.
Meanwhile, Frederick Sanger in Cambridge worked out the full amino acid order of insulin, finishing in 1955 when his group located its disulfide bonds. Insulin became the first protein to have its complete sequence determined. The work showed that every protein has a precise, defined sequence. Sanger received the 1958 Nobel Prize in Chemistry for it.
Together these advances turned peptides from vague mixtures into exact molecules with known shapes and sequences.
References
- Pauling L, Corey RB, Branson HR, The Structure of Proteins: Two Hydrogen-Bonded Helical Configurations of the Polypeptide Chain, PNAS 37:205-211 (1951)
- NobelPrize.org, Vincent du Vigneaud: Facts, Nobel Prize in Chemistry (1955)
- NobelPrize.org, Frederick Sanger: Facts, Nobel Prize in Chemistry (1958)
Educational content about laboratory research. Not medical advice. All Orion compounds are for laboratory research use only.
