ISOLATION AND CHARACTERIZATION OF AN ENZYME WITH BETA-GLUCOSIDASE ANDBETA-FUCOSIDASE ACTIVITIES FROM DALBERGIA-COCHINCHINENSIS PIERRE

A glycosidase enzyme with both beta-glucosidase and beta-fucosidase ac tivities has been purified from the seeds of Dalbergia cochinchinensis Pierre (Thai Rosewood) by ammonium sulfate fractionation, preparative isoelectric focusing, and Sephadex G-150 chromatography. The enzyme h as molecular weights of 330,000 in the native state and 66,000 in the denatured state, Hydrolysis of p-NP-beta-D-glucoside and p-NP-beta-D-f ucoside showed pH optimum at pH 5.0 and was inhibited by delta-glucono lactone, HgCl2, and p-chloromercuribenzoate. The K-m and k(cat) values of the purified enzyme were 5.4 mM and 307 s(-1) for p-NP-beta-D-gluc oside and 0.54 mM and 151 s(-1) for p-NP-beta-D-fucoside, so that the latter had by far the higher k(cat)/K-m ratio. p-NP-beta-D-galactoside , p-NP-beta-D-xyloside, and p-NP-alpha-L-arabinoside were hydrolyzed m ore slowly. Hydrolysis of sophorose, laminaribiose, and gentiobiose we re also rather slow, and hydrolysis of cellobiose was even slower. No hydrolysis of the cyanogenic glucosides linamarin or prunasin, but som e hydrolysis of amygdalin and salicin was found. Further studies are r equired to identify the natural substrates of the enzyme. However, hig h yields, ease of purification, and storage stability of the enzyme ma ke it a useful candidate for various applications, such as study of ol igosaccharide synthesis by reversal of hydrolysis.