Synthesis of Insulin

Abstract

Great strides in degradative techniques spearheaded by Sanger's pioneering work on insulin, and impressive advances in methods of isolating amino acids, peptides, and proteins during the last 20 years have exerted a dramatic influence on our knowledge of the structure of proteins. On the other hand, spectacular accomplishments in synthetic methodology and in the development of methods enabling the separation of closely related peptides (and of highly'sensitive analytic tools for assessing their chemical and stereochemical homogeneity) have set the stage for the synthesis of large polypeptide chains (1). On this basis we undertook the synthesis (1-3) of sheep insulin according to the structure postulated by Sanger (4) (Fig. 1).In this structure two polypeptide chains are present: the A chain containing 21 amino acid residues and the B chain containing 30. In the insulin molecule the two chains are linked by two disulfide bridges; there is also an intrachain disulfide bridge in the A chain that results in formation of a 20membered cyclic system. We made the assumption that if chemically synthesized A and B insulin chains, with their sulfhydryl groups free, were available, it might be possible to obtain insulin, among the probable isomers that might be formed, by air-oxidation of a mixture of the sulfhydryl forms of these chains.While the work on synthesis to- 23 DECEMBER 1966

Deciphering a Molecular Mechanism of Neonatal Diabetes Mellitus by the Chemical Synthesis of a Protein Diastereomer, [d-AlaB8]Human Proinsulin

“…Insulin has long provided a favorable model for the study of protein stability, folding, and misfolding due to its small size, amenability to chemical synthesis (49,50), and wealth of structural information (13). The present study extended the use of chemical synthesis to the human proinsulin protein molecule to investigate a DM-associated clinical mutation of the invariant Gly B8 residue.…”

Conformational Dynamics of Insulin

“…Although the latter precursor comprises a single polypeptide chain, the success of insulin chain combination (Katsoyannis, 1966) implies that chemical information required for folding is contained within the sequences of the A- and B domains (Tang and Tsou, 1990; Wang and Tsou, 1991). Studies of the disulfide-coupled folding of proinsulin and related polypeptides – foreshortened single-chain analogs (mini-proinsulin; Huang et al, 2001) and insulin-like growth factors – are notable for populated one- and two-disulfide intermediates (Hober et al, 1992; Miller et al, 1993; Qiao et al, 2001).…”

Proinsulin and the Genetics of Diabetes Mellitus

“…Although insulin biosynthesis occurs via a single-chain precursor, in vitro chemical synthesis employs isolated A-and B-peptides (42). The fidelity of chain combination implies that chemical folding information is contained within these sequences (43).…”