The kinetic properties of oleoyl-CoA:1-acyl-sn-glycero-3-phosphocholine O-acyltransferase from mouse-brain microsomes.
The kinetic properties of acylation of 1-acyl-sn-glycero(-3)phosphocholine by oleoyl-CoA were examined using mouse brain microsomes. The enzyme-catalyzed reactions were studied by measuring the rate of reaction while systematically varying the concentrations of oleoyl-CoA and 1-acylglycerophosphocholine. Double reciprocal plots of velocity versus 1-acylglycerophosphocholie produced a family of parallel lines and similar plots for oleoyl-CoA produced a family of parallel curves. Inhibition was observed at high concentrations of either substrate. By extrapolation from low substrate concentrations, the V for oleoyl-CoA:1-acylglycerophosphocholine acyltransferase in brain microsomes was found to be 6.1 nmol min-1 mg-1 and Km values were determined to be 11 microM and 107 microM for oleoyl-CoA and 1-acylglycerophosphocholine, respectively. Similar results were obtained for the enzyme-catalyzed transfer of oleoyl groups to 1-acyl-sn-glycerophosphoinositol. In this case, V was found to be 2.1 nmol min-1 mg-1 and the Km values were 4 microM and 14 microM for oleoyl-CoA and 1-acylglycerophosphoinositol, respectively. The mechanistic implications of the kinetic properties of the acyltransferases with respect to acyl group specificity for the phosphoglycerides in brain microsomes are discussed.
D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000378:metabolism*; D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D007700:Kinetics; D051379:Mice; D008815:Mice, Inbred Strains; D008861:Microsomes / Q000201:enzymology*; D013379:Substrate Specificity
D000217:Acyltransferases; D008243:1-Acylglycerophosphocholine O-Acyltransferase