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Biochem Biophys Res Commun. 2010 Jan 15;391(3):1561-6. doi: 10.1016/j.bbrc.2009.12.125. Epub 2009 Dec 28.

Oligomerization and insulin interactions of proinsulin C-peptide: Threefold relationships to properties of insulin.

Author information

1
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden. Hans.Jornvall@ki.se

Abstract

Three principally different sites of action have been reported for proinsulin C-peptide, at surface-mediated, intracellular, and extracellular locations. Following up on the latter, we now find that (i) mass spectrometric analyses reveal the presence of the C-peptide monomer in apparent equilibrium with a low-yield set of oligomers in weakly acidic or basic aqueous solutions, even at low peptide concentrations (sub-muM). It further shows not only C-peptide to interact with insulin oligomers (known before), but also the other way around. (ii) Polyacrylamide gel electrophoresis of C-peptide shows detectable oligomers upon Western blotting. Formation of thioflavin T positive material was also detected. (iii) Cleavage patterns of analogues are compatible with C-peptide as a substrate of insulin degrading enzyme. Combined, the results demonstrate three links with insulin properties, in a manner reminiscent of amyloidogenic peptides and their chaperons in other systems. If so, peripheral C-peptide/insulin interactions, absolute amounts of both peptides and their ratios may be relevant to consider in diabetic and associated diseases.

PMID:
20036640
DOI:
10.1016/j.bbrc.2009.12.125
[Indexed for MEDLINE]

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