Download MendeleySolution structure of human proinsulin C-peptide
Munte, C.E., Vilela, L., Kalbitzer, H.-R., Garratt, R.C.(2005) FEBS J 272: 4284-4293
- PubMed: 16098208
- DOI: https://doi.org/10.1111/j.1742-4658.2005.04843.x
- Primary Citation of Related Structures:
1T0C - PubMed Abstract:
The C-peptide of proinsulin is important for the biosynthesis of insulin, but has been considered for a long time to be biologically inert. Recent studies in diabetic patients have stimulated a new debate about its possible regulatory role, suggesting that it is a hormonally active peptide. We describe structural studies of the C-peptide using 2D NMR spectroscopy. In aqueous solution, the NOE patterns and chemical shifts indicate that the ensemble is a nonrandom structure and contains substructures with defined local conformations. These are more clearly visible in 50% H2O/50% 2,2,2-trifluoroethanol. The N-terminal region (residues 2-5) forms a type I beta-turn, whereas the C-terminal region (residues 27-31) presents the most well-defined structure of the whole molecule including a type III'beta-turn. The C-terminal pentapeptide (EGSLQ) has been suggested to be responsible for chiral interactions with an as yet uncharacterized, probably a G-protein-coupled, receptor. The three central regions of the molecule (residues 9-12, 15-18 and 22-25) show tendencies to form beta-bends. We propose that the structure described here for the C-terminal pentapeptide is consistent with the previously postulated CA knuckle, believed to represent the active site of the C-peptide of human proinsulin.
Organizational Affiliation:
Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil.
