Four proteins (F-IA, B, F-IIA & F-IIB), having myrosinase activity, were separated and purified from mustard powder. Each enzyme was shown to be homogeneous chromatographically, ultracentrifugally and Disc electrophoretically. Molecular weights obtained by gel-filtration and sedimentation equilibrium were 153, 000 (F-IA, F-I B & F-IIA) and 125, 000 (F-IIB). Sedimentation coefficients were 6.8S (F-IA, B & F-IIA) and 5.8S (F-11B). Stokes radius (Å), diffusion coefficient (cm²/sec) and frictional ratio (f/fo) were 47, 4.28×10^-7 and 1.33 (F-IA, B & F-III), and 43, 4.67×10^-7 and 1.29 (FIIB), respectively. Isoelectric points were pH 4.6 (F-IA, B & F-IIA) and pH 4.8 (F-IIA). The enzymes were glycoprotein with 9_??_22% carbohydrate. Amino acid composition of F-IA, Band F-IIA were very similar, but in case of F-IIB, glutamic acid, arginine and methionine contents were higher and aspartic acid and histidine contents were lower than others. The molecular weights estimated from SDS-polyacrylamide gel electrophoresis were 40, 000 (F-IA, B & F-IIA) and 30, 000 (F-IIB), respectively, and hence the enzymes are considered to have at least 4 subunits. From these results, it may be confirmed that F-IA, B & F-IIA have striking resemblances and only F-IIB is rather different.

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