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.