CONVERSION OF CARNITINE PALMITOYLTRANSFERASE OF RAT-HEART MITOCHONDRIA INTO A HIGH-AFFINITY, MALONYL-COA-INHIBITED STATE

Preincubation of rat heart mitochondria and a submitochondrial particl e derived from rat heart with malonyl-CoA lowers the IC50 of malonyl-C oA-sensitive carnitine palmitoyltransferase (CPT-I/CPT0) from 0.5 mu M and 1 mu M, respectively, for intact mitochondria and the membranous particle to 4 nM. The approximate 100-fold reduction in the ICS, for m alonyl-CoA shows that both particle and rat heart mitochondrial CPT-I/ CPT0 can be converted to a high affinity, malonyl-CoA-inhibited state with an IC50 near that of the specific inhibitors of CPT-I/CPT0 etomox iryl-CoA and tetradecylglycidyl-CoA.