Download MendeleyStructure and dynamics of des-pentapeptide-insulin in solution: the molten-globule hypothesis.
Hua, Q.X., Kochoyan, M., Weiss, M.A.(1992) Proc Natl Acad Sci U S A 89: 2379-2383
- PubMed: 1549601
- DOI: https://doi.org/10.1073/pnas.89.6.2379
- Primary Citation of Related Structures:
1HIS - PubMed Abstract:
Structures of insulin in different crystal forms exhibit significant local and nonlocal differences, including correlated displacement of elements of secondary structure. Here we describe the solution structure and dynamics of a monomeric insulin analogue, des-pentapeptide-(B26-B30)-insulin (DPI), as determined by two-dimensional NMR spectroscopy and distance geometry/restrained molecular dynamics (DG/RMD). Although the solution structure of DPI exhibits a general similarity to its crystal structure, individual DG/RMD structures in the NMR ensemble differ by rigid-body displacements of alpha-helices that span the range of different crystal forms. These results suggest that DPI exists as a partially folded state formed by coalescence of distinct alpha-helix-associated microdomains. The physical reality of this model is investigated by comparison of the observed two-dimensional nuclear Overhauser enhancement (NOE) spectroscopy (NOESY) spectrum with that predicted from crystal and DG/RMD structures. The observed NOESY spectrum contains fewer tertiary contacts than predicted by any single simulation, but it matches their shared features; such "ensemble correspondence" is likely to reflect the effect of protein dynamics on observed NOE intensities. We propose (i) that the folded state of DPI is analogous to that of a compact protein-folding intermediate rather than a conventional native state and (ii) that the molten state is the biologically active species. This proposal (the molten-globule hypothesis) leads to testable thermodynamic predictions and has general implications for protein design.
Organizational Affiliation:
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.
