원문정보
초록
영어
The whole cell bioconversion of daidzein were examined for ortho-hydroxylation using
Streptomyces avermitilis MA-4680 and Nocardia species screened from stock cultures. The
major enzymes responsible for the monohydroxylation step are cytochrome P450s. The
cytochrome P450s belong to a family of ubiquitous heme containing monooxygenases and
catalyze diverse reactions, such as hydroxylation, epoxidation, reduction, oxidation, Odemethylation, desulfonation, peroxidation, deamination and dehalogenation reactions.
Among the various reactions of cytochrome P450, hydroxylation with high regio- and stereoselectivity is of special interest for biotechnological applications. To identify monooxygenases which play a key role for the ortho-hydroxylation, 33 and dozens of
cytochrome P450s from Streptomyces avermitilis MA-4680 and Nocardia species were cloned
and examined, respectively, all the genes were constructed in E. coli BL21(DE3) host system
and each P450s was co-expressed with redox proteins, camA (putidaredoxin reductase) and
camB (putidaredoxin) from Pseudomonas putida, to produce ortho-specific
monohydroxylated daidzein(trihydroxyisoflavonoid). The major hydroxylated products of
daidzein were 7,3’,4’-trihydroxyisoflavone, 6,7,4’-trihydroxyisoflavone and 7,8,4’-
trihydroxyisoflavone which were mono-hydroxylated at ortho position of hydroxy group of
daidzein. The target P450s which showed the highest activity among the tested P450s were
prepared for the templates of the in-vitro evolution.