Calcium activated neutral protease hydrolyzes Z-disc actin [Meat tenderization, chicken breast muscle]

ABSTRACT Fractionation of myofibril proteins using Hasselebach‐Schneider solution (H‐S) and a potassium iodide solution (KI) revealed that an unusual form of actin existed in the H‐S and KI extracted myofibrils which could be easily hydrolyzed by calcium activated neutral protease (CANP). That actin was similar in amino acid composition to normal thin‐filament actin but differed in isoelectric pH, solubility in KI, and antigenicity in mice. Indirect immunofluorescence using antiserum prepared against the unusual actin established that the actin resides in the Z‐disc. The hydrolysis of actin in the Z‐disc by CANP may explain the dissolution of the Z‐disc, considered responsible for the tenderization of meat during postmortem aging.