A chymotrypsin from the Digestive Tract of California Spiny Lobster, Panulirus interruptus: Purification and Biochemical Characterization.

A chymotrypsin was purified from the gastric juice of California spiny lobster (Panulirus interrutpus), using preparative electrophoresis and affinity chromatography on agarose-p-aminobenzamidine. The molecular mass was estimated by polyacrylamide gel electrophoresis (SDS-PAGE) under denaturing conditions to be 28 kDa. Chymotrypsin activity was totally inhibited by phenylmethylsulfonyl fluoride (PMSF) and chymostatin.

Biochemical characterisation of chymotrypsin from the midgut gland of yellowleg shrimp, Penaeus californiensis.

Chymotrypsin from shrimp, Penaeus californiensis, was compared to Bos taurus chymotrypsin, and its structure-function relationship was studied. Catalytic efficiency toward synthetic substrate is lower, but it has a broad specificity and higher activity toward protein substrates, including collagen. It is active at pH 4-10 and fully active up to 50 °C for 2 h and at least nine days at room temperature.

Phenoloxidase activity of hemocyanin in whiteleg shrimp Penaeus vannamei: conversion, characterization of catalytic properties, and role in postmortem melanosis.

Latent phenoloxidase activity of hemocyanin (Hc) in whiteleg shrimp Penaeus vannamei was assayed to determine its potential involvement in postmortem melanosis. Conversion of pure 12-mer, but not 6-mer, hemocyanin to phenoloxidase by endogenous (serine proteinases) and exogenous (SDS) effectors demonstrated the need of complex aggregation for displaying enzyme activity. Because Hc was converted to Hc-phenoloxidase (HcPO) by hemocytes extracts, the mechanism of conversion seems to be the same for polyphenoloxidases.