On the 4'-phosphopantetheine content of chicken and rat liver fatty acid synthetases

The finding that animal synthetases are complexes consisting of two polypeptide chains (Stoops, J.K., Arslanian, M.J., Oh, Y.H., Vanaman, T.C., and Wakil, S.J. (1975) Proc. Natl. Acad. Sci. U. S. A. 72, 1940-1944) led us to investigate their 4'-phosphopantetheine content. We have found that the chicken and rat synthetases contain 1.6 to 2.2 mol of 4'-phosphopantetheine per mol of the complex. The implications of this finding concerning the structure of the complex and the biosynthetic pathway of fatty acid synthesis are discussed.