Transcript Lectures 1-3: Review of forces and elementary statistical

Insulin
Insulin: the protein of the 20th century
• One of the first proteins crystallized in 1926 (Structural Genomics)
• First protein fully sequenced in 1955 (Bioinformatics)
• First protein chemically synthesized in 1958
• First human protein manufactured via recombinant in 1979 (Biotechnology)
Studying the three-dimensional structure of insulin
As described above, human insulin consists of 51 amino acids, divided into two chains,
commonly labeled A and B, with 21 and 30 amino acids respectively. The chains are
linked by three disulfide bridges, two forming inter-chain cystine at A7-B7 and A20-B19,
and one forming an intra-chain cystine at A6-A11. A piece of anti-parallel b-sheet is
formed upon dimerization: residues B23 to B28 of one monomer lie anti-parallel to the
same stretch in the other monomer. There are two very small a-helices in the A chain, and
a three turn a-helix running from residues B9 to B19 is found in every insulin structure
known so far.