Neutral calcium-activated proteases from European sea bass (Dicentrarchus labrax L.) muscle: polymorphism and biochemical studies

Calcium-dependent proteinases or calpains were studied in fish muscle. Hydr ophobic chromatography, followed by anion-exchange chromatography of the so luble fraction of sea bass white muscle proteins, resulted in three peaks o f calcium-dependent protease activity at neutral pH (A, B and C). They are all neutral cysteine calcium-activated proteinases and can, therefore, be c lassified as calpain-like enzymes. From the Ca2+ concentration required for activity, A is a mu-calpain, and B and C are m-calpains. They share many p roperties with calpains from other vertebrate cells but differ in native ma ss, subunit composition, and the unusual numbers in which they are present. Their specific pattern of expression throughout the year could be of great importance to the resulting rate and extent of degradation of fish flesh a fter death. (C) 2000 Elsevier Science Inc. All rights reserved.