Purification and characterization of radish myrosinase
1989
Kim, M.R. (Chungnam National Univ., Taejon (Korea R.). Dept. of Food and Nutrition) | Lee, H.S. (Seoul National Univ., Seoul (Korea R.). Dept. of Food and Nutrition)
The purification of myrosinase from radish roots was performed using Concannavalin A-Sepharose affinity chromatography and gel permeation HPLC, which gave a 22-fold-purification (S.P.A.= 39,000 units/mg) with 50% recovery, SDS-polyacrylamide gel electrophoresis showed a single major band, suggestive of a relatively pure myrosinase, and the M.W. of the enzyme determined on gel permeation HPLC was ca. 124K. The enzyme showed an optimum pH of 6.5 and was stable at pH 6 to 7 at room temperature, but unstable below pH 4. The enzyme possessed an optimum temperature of 37deg C, and gave a Vmax value of 40 micro moles/mg.min and a Km value of 0.12mM for sinigrin. The purified myrosinase was activated maximally by 0.6mM of ascorbic acid, but somewhat inhibited by more than 2mM ascorbic acid. The activities of myrosinase present in the peelings and the peeled radish amounted to approximately 1,333 units/g and 140 units/g weight, respectively and the peelings contained much more myrosinase activity than the peeled radish
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