Selectivity of acyl transfer between phospholipids: arachidonoyl transacylase in dog heart membranes.

Dog heart microsomes catalyze the transfer of acyl groups from the sn-2 position of exogenous phosphatidylcholine to 1-acyl lysophosphatidylethanolamine. Approximately equal amounts of free fatty acids are produced as well. The reaction exhibits a pH optimum of 7.5-8.5 and does not require Ca2+ or other divalent cations. The reaction proceeds in the absence of exogenous coenzyme A but acyl transfer is enhanced by its addition. The transacylase exhibits a strong preference for arachidonate over linoleate and thus may be involved in the maintenance of the high amounts of arachidonate found in microsomal ethanolamine phospholipids.