Comparison of Properties of Carnitine Palmitoyltransferase I with Those of Carnitine Palmitoyltransferase II, and Preparation of Antibodies to Carnitine Palmitoyltransferases

Abstract

Abstract Carnitine palmitoyltransferase II has been partially purified. Its properties have been found to differ from those of carnitine palmitoyltransferase I (EC 2.3.1.23) in the following ways. (a) Carnitine palmitoyltransferase II catalyzes the reaction only in the direction towards long chain fatty acyl-CoA formation. (b) Carnitine palmitoyltransferase II requires preincubation with CoA-SH for manifestation of catalytic activity. (c) Carnitine palmitoyltransferase II shows greater chain-length substrate specificity for the transfer of long chain fatty acyl groups from (-)-acylcarnitine derivatives to CoA-SH, with greatest activity being obtained in the transfer of stearoyl and palmitoyl groups. (d) Carnitine palmitoyltransferase II activity is inhibited by shorter chain-length fatty acylcarnitine derivatives. The apparent molecular weight of carnitine palmitoyltransferase II, the same as that of carnitine palmitoyltransferase I, is 150,000. Antibodies were prepared from the serum of each of three rabbits injected with apparently homogeneous preparations of purified carnitine palmitoyltransferase I. Sera obtained from all rabbits inhibited the activity of carnitine palmitoyl-transferase I. However, serum obtained from one rabbit unexpectedly inhibited the activity of carnitine palmitoyl-transferase II. The data were discussed in relation to the possibility that carnitine palmitoyltransferase II is a transformed product of carnitine palmitoyltransferase I, since carnitine palmitoyltransferase II could be obtained from carnitine palmitoyltransferase I by treatment with urea or guanidine under certain conditions.