ENZYMIC ACTIVITIES IN PRE-RIGOR AND POST-RIGOR SARCOPLASMIC EXTRACTS OF CHICKEN PECTORAL MUSCLE

Abstract

It was confirmed that myogen (extracted in hypotonic salt solutions) and sarcoplasm (obtained by gentle homogenization in hypertonic sucrose solutions) from chicken pectoral muscle differ in content of certain cationic components. One of the proteins reduced in sarcoplasm was identified as the lactate dehydrogenase isozyme characteristic of skeletal muscle, and it exhibited changes in recovery and activity consistent with the sequence reported for sarcoplasmic proteins through rigor and postmortem "aging". At the same time the distinction between two esterase zones, specific respectively for myogen and for sarcoplasm, tended to be obliterated. Electrophoretic patterns and activities of malate dehydrogenase, isocitrate dehydrogenase, alkaline phosphatase, and acid phosphatase showed no specific dependence on conditions of extraction or of aging. These observations are discussed in terms of possible associations between these components and intracellular structures, notably lysosomes and sarcoplasmic reticulum, which may be labilized by incipient autolysis, ultimately manifest as "tenderization" of the muscle tissue.