The effect of conditions of homogenization on the activity of pyruvate dehydrogenase and its stability in brain homogenates.
The activity of pyruvate dehydrogenase was higher in brain homogenates prepared by using a Potter-Elvehjem type homogenizer (79.0 +/- 2.38 nmol/min/mg of protein) than by using an Ultra-Turrax homogenizer (from 62.39 +/- 1.35 to 74.60 +/- 1.21 nmol/min/mg of protein). Different conditions of homogenization with the Ultra-Turrax had no significant effect on the activity of pyruvate dehydrogenase. Pyruvate dehydrogenase activity decreased significantly in brain homogenates maintained at 0 degrees C for short periods or stored at ?20 degrees C for several days. Marked differences in pyruvate dehydrogenase activities reported in earlier work have been attributed to its instability in brain homogenates. The results showed that pyruvate dehydrogenase is not a rate limiting enzyme in the metabolism of glucose in brain in vivo.
Gaitonde
M K
MK
Department of Biochemistry, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, England.
Murray
E
E