Kinetic properties of purified carnitine acetyltransferase from the skeletal muscle of Arabian camel (Camelus dromedarius)

The kinetic properties of carnitine acetyltransferase from the skeletal muscle of the Arabian camel (Camelus dromedarius) were studied. The enzyme showed an optimum pH between 7.2 and 8.2. Reciprocal plots of data obtained by varying one substrate concentration while keeping the other constant revealed lines that converged on the abscissa, indicating that the enzyme possibly follows a random mechanism of catalysis. The K(m)s for L-carnitine and acetyl-coenzyme A were 244 and 44 mu M respectively, while those for acetyl-DL-carnitine and coenzyme A (Co A)were 307 and 39 mu M respectively. The K-m for one substrate was found to be independent of the concentration of the second substrate used. Corresponding V-max values for L-CA, acetyl-Co A, acetyl DL-carnitine and Co A are 98, 98, 102 and 100 mu mol min(-1) mg(-1) protein respectively. The low K-m obtained for acetyl-DL-carnitine suggests an adaptive mechanism in this desert species for enduring prolonged dry spells without food and water.