1K3M

NMR STRUCTURE OF HUMAN INSULIN MUTANT ILE-A2-ALA, HIS-B10-ASP, PRO-B28-LYS, LYS-B29-PRO, 15 STRUCTURES

Summary for 1K3M

• Entry DOI: 10.2210/pdb1k3m/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: 5752.51

Authors

Xu, B.,Hua, Q.-X.,Nakagawa, S.H.,Jia, W.,Chu, Y.-C.,Katsoyannis, P.G.,Weiss, M.A. (deposition date: 2001-10-03, release date: 2001-10-17, Last modification date: 2024-10-30)

Primary citation

Xu, B.,Hua, Q.X.,Nakagawa, S.H.,Jia, W.,Chu, Y.C.,Katsoyannis, P.G.,Weiss, M.A.
A cavity-forming mutation in insulin induces segmental unfolding of a surrounding alpha-helix.
Protein Sci., 11:104-116, 2002

PubMed Abstract: To investigate the cooperativity of insulin's structure, a cavity-forming substitution was introduced within the hydrophobic core of an engineered monomer. The substitution, Ile(A2)-->Ala in the A1-A8 alpha-helix, does not impair disulfide pairing between chains. In accord with past studies of cavity-forming mutations in globular proteins, a decrement was observed in thermodynamic stability (DeltaDeltaG(u) 0.4-1.2 kcal/mole). Unexpectedly, CD studies indicate an attenuated alpha-helix content, which is assigned by NMR spectroscopy to selective destabilization of the A1-A8 segment. The analog's solution structure is otherwise similar to that of native insulin, including the B chain's supersecondary structure and a major portion of the hydrophobic core. Our results show that (1) a cavity-forming mutation in a globular protein can lead to segmental unfolding, (2) tertiary packing of Ile(A2), a residue of low helical propensity, stabilizes the A1-A8 alpha-helix, and (3) folding of this segment is not required for native disulfide pairing or overall structure. We discuss these results in relation to a hierarchical pathway of protein folding and misfolding. The Ala(A2) analog's low biological activity (0.5% relative to the parent monomer) highlights the importance of the A1-A8 alpha-helix in receptor recognition.

PubMed: 11742127
DOI: 10.1110/ps.ps.32102

Experimental method

SOLUTION NMR