title: Kinetic properties of purified carnitine acetyltransferase from the skeletal muscle of Arabian camel (Camelus dromedarius).
abstract: 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 possible follows a random mechanism of catalysis. The Kms for L-carnitine and acetyl-coenzyme A were 244 and 44 microM respectively, while those for acetyl-DL-carnitine and coenzyme A (Co A) were 307 and 39 microM respectively. The Km for one substrate was found to be independent of the concentration of the second substrate used. Corresponding Vmax values for L-CA, acetyl-Co A, acetyl-DL-carnitine and Co A are 98, 98, 102 and 100 mumol min-1 mg-1 protein respectively. The low Km obtained for acetyl-DL-carnitine suggests an adaptive mechanism in this desert species for enduring prolonged dry spells without food and water.
authors.affiliation: Biochemistry Department, College of Science, King Saud University, Saudi Arabia.
authors.forename: A S
authors.initials: AS
authors.lastname: Alhomida
authors.forename: A A
authors.initials: AA
authors.lastname: al-Jafari
authors.forename: A S
authors.initials: AS
authors.lastname: Duhaiman
authors.forename: N
authors.initials: N
authors.lastname: Rabbani
authors.forename: M A
authors.initials: MA
authors.lastname: Junaid
mesh_terms: D000105:Acetyl Coenzyme A / Q000378:metabolism; D000108:Acetylcarnitine / Q000378:metabolism; D000818:Animals; D002162:Camelus; D002331:Carnitine / Q000378:metabolism; D002332:Carnitine O-Acetyltransferase / Q000302:isolation & purification / Q000378:metabolism*; D003065:Coenzyme A / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018482:Muscle, Skeletal / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D000108:Acetylcarnitine; D000105:Acetyl Coenzyme A; D002332:Carnitine O-Acetyltransferase; D002331:Carnitine; D003065:Coenzyme A