Abstract.
Degradation of proinsulin C-peptide in mouse kidney and human placenta extracts was studied using reverse-phase high-performance liquid chromatography and nano-electrospray mass spectrometry. In total, 15 proteolytic cleavage sites were identified in human and mouse C-peptides. Early sites included the peptide bonds N-terminal of Val/Leu10, Leu12, Leu21, Leu24 and Leu26 in different combinations for the two tissues and two peptides. Notably, these cleavages were N-terminal of a hydrophobic residue, and all but one N-terminal of Leu. A late degradation product of the human peptide detected in the kidney extract was the C-terminal hexapeptide, containing just one residue more than the biologically active C-terminal pentapeptide of C-peptide. We conclude that the degradation of C-peptide in kidney and placenta follows similar patterns, dominated by endopeptidase cleavages N-terminal of Leu.
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Received 21 July 2004; received after revision 6 October 2004; accepted 6 October 2004
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Melles, E., Jörnvall, H., Tryggvason, S. et al. Degradation of proinsulin C-peptide in kidney and placenta extracts by a specific endoprotease activity. CMLS, Cell. Mol. Life Sci. 61, 2979–2982 (2004). https://doi.org/10.1007/s00018-004-4313-7
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DOI: https://doi.org/10.1007/s00018-004-4313-7