Acta Biochimica et Biophysica 7. (1972)
1972 / 2. szám - I. Alkonyi-A. Sándor: Demonstration of an Enzymatic Transfer Reaction between ß-Methyl-crotonyl-Coenzyme A and L-carnitine (Short Communication)
Acta Biochim. et Biophys. Acad. Sei. Hung. Vol. 7 (2), pp. 149 — 150 (1972) Demonstration of an Enzymatic Transfer Reaction between (3-Methyl-crotonyl-Coenzyme A and L-Carnitine (Short Communication) I. Alkonyi, A. Sándor Institute of Biochemistry, University Medical Scchool, Pécs, Hungary (Received January 28, 1972) During the last ten years a considerable body of evidence has been accumulated for the important role of the macroergic compounds of various acids with L-carnitine in the living cell, in addition to the CoA* esters (Bressler, 1970). The reversible transfer of various acyl groups from the SH-group of CoA to the OH-group of L-carnitine is brought about by specific transferases. These partly mitochondrial and partly extramitochondrial enzymes are presumably involved in transport and regulatory processes (Bressler, Brendel, 1966). First the acetyltransferase enzyme (Acetyl-CoA: carnitine O-acetyl-transferase, EC 2.3.1.7) was discovered by Friedman and Fraenkel (1955) in an extract of pigeon liver acetone powder. Fritz et al. (1963) succeeded in the purification of this enzyme from pig heart to a specific activity of 4.6. Fritz et al. reported data about the specificity with regard to carbon atom number, but these results are not very reliable because the enzyme preparation used was not sufficiently pure. However, it is noteworthy that this enzyme was completely inactive towards palmityl-CoA. The enzyme was crystallized by Chase et al. (1965) from pigeon breast muscle and this preparation had a specific activity of 119. However, these authors did not examine the specificity with regard to carbon atom number. The enzyme catalyzing the transfer of palmitoyl group was demonstrated by Bremer (1962) in rat heart mitochondrial membrane (Norum, Bremer, 1967). Recently Solberg ( 1971) found in the carnitineacetyl-transferase preparation (specific activity: 80) of Boehringer Ltd. a foreign activity which differed from the acetyltransferase enzyme and was specific for fatty acids containing 6 to 10 carbon atoms. Solberg denoted this enzyme as carnitine-octanoyl transferase. The investigations described so far are pertinent only to the carnitine esters of aliphatic fatty acids. In the present work we examined whether the following reaction can be catalyzed enzymatically : /Lmethyl-crotonyl-CoA + L-carnitine ^2 /1-methyl-crotonyl-L-carnitine + CoA The search for such an activity is justified by the fact that /1-methyl-crotonyl-CoA plays an important role in steroid synthesis (Decker, 1959). In the experiments we used carnitine-acetyltransferase (Boehringer) of specific activity 80. The /1-methyl-crotonyl-CoA was prepared according to the * Abbreviations: CoA, coenzyme A; EDTA, ethylenediamine tetraacetic acid. Acta Biochimica et Biophysica Academiae Scientiarum Hungaricae 7, 1972