Degradation of proinsulin C-peptide in kidney and placenta extracts by a specific endoprotease activity |
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Authors: | E?Melles H?J?rnvall S?Tryggvason K?Gemzell?Danielsson K?Ekberg K?Tryggvason J?Wahren Email author" target="_blank">T?BergmanEmail author |
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Institution: | Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden. |
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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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