ABSTRACT
A number of mammalian tissues have significant quantities of plasmenylcholine and/or plasmanylcholine. Structural studies of phosphatidylcholine (PC) indicate that there is an asymmetric distribution of acyl groups on the molecule. Cardiac lysoPC-lysoPC transacylase has been purified from rabbit heart cytosol. The purified cardiac enzyme is similar to the lung enzyme in possessing both transacylase and lysophospholipase activities. The transacylase/lysophospholipase ratio of the purified cardiac enzyme was 0.5, which is different from the ratio for the lung enzyme. In general the specific activity of the nuclear enzyme was greater than the microsomal enzyme, although this varied with the composition and concentration of the acyl acceptor as well as the nature of the acyl donor. The rabbit heart mitochondrial enzyme was active with a range of acyl CoAs, and the rate of incorporation of the acyl groups was similar to that of the microsomal acyltransferase.
