%0 Journal Article
%T pH-Dependent Interaction between C-Peptide and Phospholipid Bicelles
%A Sofia Unnerst le
%A Lena M ler
%J Journal of Biophysics
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/185907
%X C-peptide is the connecting peptide between the A and B chains of insulin in proinsulin. In this paper, we investigate the interaction between C-peptide and phospholipid bicelles, by circular dichroism and nuclear magnetic resonance spectroscopy, and in particular the pH dependence of this interaction. The results demonstrate that C-peptide is largely unstructured independent of pH, but that a weak structural induction towards a short stretch of β-sheet is induced at low pH, corresponding to the isoelectric point of the peptide. Furthermore, it is demonstrated that C-peptide associates with neutral phospholipid bicelles as well as acidic phospholipid bicelles at this low pH. C-peptide does not undergo a large structural rearrangement as a consequence of lipid interaction, which indicates that the folding and binding are uncoupled. In vivo, local variations in environment, including pH, may cause C-peptide to associate with lipids, which may affect the aggregation state of the peptide.
%U http://www.hindawi.com/journals/jbp/2012/185907/