[Lipoamide dehydrogenase, citrate synthase and beta-hydroxyacyl-CoA-dehydrogenase in skeletal muscles. VI. Influence of freezing (-20 degrees C) and thawing of bovine, calf and porcine muscle on activity and subcellular distribution].

Freezing of bovine, calf, and porcine skeletal muscles at -20 degrees C before or after rigor mortis and thawing at room temperature did not cause significant changes in the total activities of the mitochondrial enzymes lipoamide dehydrogenase, citrate synthase, and beta-hydroxyacyl-CoA-dehydrogenase. Freezing (pre or post rigor) and thawing result in a partial release of these enzymes from their binding to the inner membrane of the mitochondria. The transfer of enzyme activity into the sarcoplasmic fluid is due to damage of the mitochondrial membranes by freezing and thawing of the muscle tissue. During longer storage of the muscle at +2 degrees C the mitochondria become more labile towards freezing which may be recognised from an increased release of the enzymes (particularly in porcine muscle). Repeated freeze/thaw cycles cause an increase in the release of the three enzymes.