Identification of A chain cleavage sites in intact insulin produced by insulin protease and isolated hepatocytes

William C. Duckworth, Frederick G. Hamel, Juris J. Liepnieks, Daniel E. Peavy, Michael P. Ryan, Mark A. Hermodson, Bruce H. Frank

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The degradation of insulin by the enzyme insulin protease and by isolated hepatocytes results in proteolytic cleavages in both the A and B chains of intact insulin. Previous studies have shown that one of the A chain cleavages is between A13 leucine and A14 tyrosine and that a second cleavage occurs carboxyl to the A14 residue. In the present study we have used insulin specifically iodinated on the A19 tyrosine and examined the A chain cleavages by the enzyme and by hepatocytes. Insulin degradation products were purified by HPLC and sequenced by automated Edman degradation. Only two A chain cleavage sites were identified, one the previously reported A13-A14 and the other between A14 tyrosine and A15 glutamine. These data thus identify the second A chain cleavage site and further support the role of insulin protease in hepatic metabolism of insulin.

Original languageEnglish (US)
Pages (from-to)615-621
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume147
Issue number2
DOIs
StatePublished - Sep 15 1987

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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