1LKQ

NMR STRUCTURE OF HUMAN INSULIN MUTANT ILE-A2-GLY, VAL-A3-GLY, HIS-B10-ASP, PRO-B28-LYS, LYS-B29-PRO, 20 STRUCTURES

Summary for 1LKQ

• Entry DOI: 10.2210/pdb1lkq/pdb
• Descriptor: INSULIN (2 entities in total)
• Functional Keywords: hormone, human insulin, mutant, hormone-growth factor complex, hormone/growth factor
• Cellular location: Secreted: P01308 P01308
• Total number of polymer chains: 2
• Total formula weight: 5696.41

Authors

Weiss, M.A.,Hua, Q.X.,Chu, Y.C.,Jia, W.,Philips, N.F.,Wang, R.Y.,Katsoyannis, P.G. (deposition date: 2002-04-25, release date: 2002-05-22, Last modification date: 2024-10-30)

Primary citation

Hua, Q.X.,Chu, Y.C.,Jia, W.,Phillips, N.F.,Wang, R.Y.,Katsoyannis, P.G.,Weiss, M.A.
Mechanism of insulin chain combination. Asymmetric roles of A-chain alpha-helices in disulfide pairing
J.Biol.Chem., 277:43443-43453, 2002

PubMed Abstract: The A and B chains of insulin combine to form native disulfide bridges without detectable isomers. The fidelity of chain combination thus recapitulates the folding of proinsulin, a precursor protein in which the two chains are tethered by a disordered connecting peptide. We have recently shown that chain combination is blocked by seemingly conservative substitutions in the C-terminal alpha-helix of the A chain. Such analogs, once formed, nevertheless retain high biological activity. By contrast, we demonstrate here that chain combination is robust to non-conservative substitutions in the N-terminal alpha-helix. Introduction of multiple glycine substitutions into the N-terminal segment of the A chain (residues A1-A5) yields analogs that are less stable than native insulin and essentially without biological activity. (1)H NMR studies of a representative analog lacking invariant side chains Ile(A2) and Val(A3) (A chain sequence GGGEQCCTSICSLYQLENYCN; substitutions are italicized and cysteines are underlined) demonstrate local unfolding of the A1-A5 segment in an otherwise native-like structure. That this and related partial folds retain efficient disulfide pairing suggests that the native N-terminal alpha-helix does not participate in the transition state of the reaction. Implications for the hierarchical folding mechanisms of proinsulin and insulin-like growth factors are discussed.

PubMed: 12196530
DOI: 10.1074/jbc.M206107200

Experimental method

SOLUTION NMR