Effect of carnitine analogs on carnitine acetyltransferase

Carnitine analogs with various substituents on the nitrogen were tested for their effect on carnitine acetyltransferase from rat sperm and pigeon breast. A radiometric assay was used to measure the formation of acetylcarnitine in the presence of other enzymes that competed for acetyl coenzyme A in the sperm preparation. The apparent enzyme inhibition caused by the analogs was explained by the analogs serving as alternative substrates with higher Km and lower Vmax values. The analogs had no effect on whole sperm.