Proteinase in Pacific whiting surimi wash water: Identification and characterization

A proteinase in Pacific whiting surimi wash water (SWW) was characterized to be cathepsin L based on molecular mass (M(r)), substrate specificity, and SDS-substrate gel electrophoresis. The proteinase was highly active on Z-Phe-Arg-NMec, and the native M(r) was 27,400 based on size exclusion (SEC)-HPLC. Acidification of the SEC-HPLC fractions showed a two-fold increase in activity on Z-Phe-Arg-NMec. SWW proteolytic activity was found at M(r) 54,200 on SDS-substrate gel. However, acidification shifted the activity zone to M(r) 39,500 corresponding to cathepsin L. No evidence of activity by calpain or cathepsin B or H was found in Pacific whiting SWW.