PURIFICATION AND CHARACTERIZATION OF THE MAIN PEPSINOGEN FROM THE SHARK, CENTROSCYMNUS-COELOLEPIS

The main pepsinogen from the mucosa of the shark, Centroscymnus coelol epis, has been purified and characterized. This zymogen, the most abun dant protein in terms of quantity and activity (yield 72%), is a homog eneous monomer of molecular weight 42 +/- 0.7 kDa, as determined by el ectrophoresis, The aspartyl proteinase nature of this enzyme was confi rmed by the considerable inhibition by pepstatin, Its specificity as t o the oxidized B-chain of bovine insulin was determined using electros pray ionization mass spectrometry (ESI-MS) coupled with reversed phase high pressure liquid chromatography (RP-HPLC). The 15-16 Leu-Tyr bond was rapidly cleaved in this substrate, followed by the 24-25 Phe-Phe, 25-26 Phe-Tyr, and 11-12 Leu-Val bonds.