Enzymatic Synthesis of 4-Hydroxyphenyl β-D-Oligoxylosides and Their Notable Tyrosinase Inhibitory Activity
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY(2009)
摘要
We have purified and characterized an oligoxylosyl transfer enzyme (OxtA) from Bacillus sp. strain KT12. In the present study, a N-terminally His-tagged recombinant form of the enzyme, OxtA(H)(E), was overproduced in Escherichia coli and applied to the reaction with xylan and hydroquinone to produce 4-hydroxyphenyl beta-D-oligoxylosides, beta-(Xyl)(n)-HQ (n = 1-4), by one step reaction. The obtained beta-(Xyl)(n)-HQ inhibited mushroom tyrosinase, which catalyzes the oxidation of L-DOPA to L-DOPA quinine, and the IC50 values of beta-Xyl-HQ, beta-(Xyl)(2)-HQ, beta-(Xyl)(3)-HQ, and beta-(Xyl)(4)-HQ were 3.0, 0.74, 0.48, and 0.18 mM respectively. beta-(Xyl)(4)-HQ showed 35-fold more potent inhibitory activity than P-arbutin (4-hydroxyphenyl beta-D-glucopyranoside), of which the IC50 value was measured to be 6.3 mM. Kinetic analysis revealed that beta-(Xyl)(2)-HQ, beta-(Xyl)(3)-HQ, and beta-(Xyl)(4)-HQ competitively inhibited the enzyme, and the corresponding K-i values were calculated to be 0.20, 0.29, and 0.057 mM respectively.
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关键词
transxylosylation,tyrosinase inhibitors,4-hydroxyphenyl beta-oligoxylosides
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