The propeptide converting enzyme PC1 prefers proinsulin over fluorescent peptide analogs as its substrate

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The processing of proinsulin is being used in our laboratory to examine the selectivity demonstrated by propeptide converting enzymes. PC1 is responsible for the cleavage of the B-chain/Cpeptide junction in proinsulin. We have recently succeeded in generating recombinant human proinsulin (hPI) from bacteria, and PC1 using a baculovirus system. We have also developed an in vitro assay and are now attempting to determine kinetic constants for the action of a converting enzyme with its authentic substrate. Our initial results indicate that the Km for hPI is approximately 2 iiM compared to 25 nM for Pyr-RTKR-AMC. In the absence of an active site directed probe, RIA determination of enzyme concentration provides a lower limit for /tcat of 1 s-' for hPI and 0.5 S'1 for PyrRTKR-AMC. From this, the ratios of the specificity constants C

Original languageEnglish (US)
Pages (from-to)A1225
JournalFASEB Journal
Issue number9
StatePublished - Dec 1 1997


All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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