The objectives of this project are two-fold. One objective is to determine the effect of varying fatty acid composition on several membranous enzymes of an unsaturated fatty acid auxotroph of E. coli. The enzymes acyl CoA glycerol-3-phosphate aclytransferase, acyl CoA monoacylglycerol-3-phosphate acyltransferase, glycerol-3-phosphate dehydrogenase, succinic dehydrogenase, NADH dehydrogenase and NADH oxidase will be studied. Temperature characteristics, substrate specificity and susceptibility to inhibitors are some of the parameters of these enzymes which will be studied as a function of varying fatty acid composition of membrane phospholipids. Phase changes in membrane phospholipids will be measured by differential scanning calorimetry. Correlation between lipid phase changes and the effect of temperature on various parameters of membranous enzymes will be investigated. The second objective of this project is to study the acylation of glycerol-3-phosphate in rat lung. The specificity of acylation with respect to saturated versus unsaturated fatty acids will be investigated in an attempt to identify an enzyme involved in synthesis of dipalmitoyl lecithin, the principal component of lung surfactant. Isolation and characterization of such an enzyme will be attempted.