Sequence of a tryptic peptide from the NADPH binding site of the enoyl reductase domain of fatty acid synthase.

Fatty acid synthase from the uropygial gland of goose was inhibited by treatment with pyridoxal 5'-phosphate by selectively modifying a lysine residue at the NADPH binding site of the enoyl reductase domain (A. J. Poulose and P. E. Kolattukudy (1980) Arch. Biochem. Biophys. 201, 313-321). Distribution of radioactivity in tryptic peptides generated from the synthase treated with pyridoxal 5'-phosphate/NaB3H4 in the presence and absence of 2'-monophosphoadenosine-5'-diphosphoribose, which protects the enzyme from inactivation by pyridoxal phosphate, showed that modification of one specific peptide was prevented by the protector. This peptide was purified by a combination of Sephadex G-25 column chromatography, anion-exchange chromatography, and high-performance liquid chromatography. The primary structure of this peptide is Val-Phe-Thr-Thr-Val-Gly-Ser-Ala-Glu-Lys(Pxy)-Arg.