EFFECT OF HIGH TEMPERATURE CONDITIONING ON SUBCELLULAR DISTRIBUTION AND LEVELS OF LYSOSOMAL ENZYMES

The control (C) side of 23 animals was placed in a 2°C chill room at 1 hr postmortem, while the other side was high temperature cdnditioned (HT) at approximately 22°C for 4 hr postmortem, at 12°C for an additional 8 hr and was then placed in the 2°C chill room. The activity of cathepsin C and β-glucuronidase was measured on the nuclear, micro somal, and unsedimentable fractions at 12, 18 and 24 hr postmortem in order to determine the amount of sedimentable and free enzyme activity at these postmortem times. High temperature conditioning enhances the disruption of the lysosomal membrane as evidenced by a significant increase in percent of free enzyme activity at 12 hr postmortem for both cathepsin C and β-glucuronidase. There was also a significant decrease in total activity for both enzymes of the HT group at 12 hr postmortem due to autolysis of the free enzyme. These differences were not present at 18 and 24 hr postmortem (except for decreased total activity of cathepsin C at 18 hr), indicating that differences caused by high temperature conditioning take place very early postmortem and that the differences in enzyme activities are not detectable at later postmortem times. These results indicate that some of the differences in tenderness produced by HT treatments are possibly associated with the increased level of free lysosomal enzymes during the first 12 hr postmortem.