The mechanisms involved in the biosynthesis of saturated and unsaturated fatty acids will be investigated. Fatty acid synthetases of animal tissues are multifunctional enzymes containing two polypeptide chains of molecular weights of 200,000 to 220,000. Since the subunits have the component activities involved in fatty acid synthesis, the polypeptides are multifunctional enzymes containing several active sites on single polypeptide chains. We plan to study the structural and functional properties of these enzymes. Physical as well as chemical and biochemical approaches will be employed. The interaction of the subunits to form the active synthetase will be established through studies with the ultra-centrifuge and electron microscope. The individual enzymes and the 4'-phosphopantetheine containing protein (ACP) will be isolated from the synthetase after cleaving the latter with various proteases. Acyl derivatives of ACP will be prepared and utilized in determining the properties of these enzymes. Attempts will be made to reconstitute the active synthetase by reassociating the individual components. The structure of the yeast fatty acid synthetase will be studied and the results compared to that of animal synthetase. 125I-antibodies against synthetase will be used for the isolation of the polysomes and mRNA of fatty acid synthetase. Effect of diet and hormones on the formation of mRNA and its translation to synthetase will be investigated in both adult and embryonic animals. Studies of the functions of lipids in biological membranes will include investigations of the effects of changes in fatty acid composition of membrane lipids and of the physical state of membrane phospholipids on the binding and insertion of proteins in membranes. The interaction of these proteins with other membrane components yielding membrane active systems will be investigated also. Methodology to be employed includes enzymology, protein chemistry, lipid chemistry and cell biology.