Chemical Properties of Major Subunit of Rice Bran Lipase

The molecular weight of rice bran lipase was evaluated to be 32,000 by sodium dodecy 1 sulfate polyacrylamide gel electrophoresis and gel filtration through Sepharose 6B in 6 N guanidium chloride. The amino-terminal amino acid of the enzyme protein was determined to be glutamic acid by the dansyl chloride method and the phenylisothiocyanate method. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of dithiothreitol reduced enzyme protein demonstrated that the enzyme protein consisted of subunits held together through disulfide bond(s). Gel filtrations of the dithiothreitol reduced and the performic acid oxidized lipase through Sephadex G-150 in the presence of 1 % sodium dodecyl sulfate effected the isolation of a subunit with a molecular weight of 14,000. The isolated subunit comprised amino acids; Asp15 Thr8 Ser11 Glu11 Pro9 Gly20 Ala16 Val7 Met2 Ile4 Leu7 Tyr7 Phe6 Lys5 His2 Arg6 1/2 Cys6.