Characterization of Enzymes That Degrade Crab Exoskeleton: II. Two Acid Proteinase Activities

Document Type

Article

Publication Date

1-1-1988

Description

Specific proteins extracted from the membranous layer of the exoskeleton of the Bermuda land crab, Gecarcinus lateralis, are degraded at acid pH values by two proteinase activities (AP I and AP II) extracted from integumentary tissues. The pH optimum of AP I was about 5; it does not bind to cation exchange resin and was strongly inhibited by pepstatin A. The pH optimum of AP II was about 4; it binds to a cation exchange resin and was inhibited by cysteine proteinase inhibitors. AP II shared some characteristics with the human lysosomal proteinase cathepsin B. Unlike cathepsin B, which binds to the cysteine proteinase inhibitor E‐64 in a 1:1 ratio, AP II was not completely inhibited by E‐64, and only at the lower concentrations of inhibitor was there a linear relationship between enzyme activity and amount of inhibitor.

Share

COinS