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  • Rational design of novel mutants of fungal 17beta-hydroxysteroid dehydrogenase
    Kristan, Katja, 1975- ...
    Reduction of 17-ketosteroids is a biocatalytic process of economic significance for the production of steroid drugs. This reaction can be catalyzed by different microbial 17beta-hydroxysteroid ... dehydrogenases (17beta-HSD), like the 17beta-HSD activity of Saccharomyces cerevisiae, Pichiafaranosa and Mycobacterium sp., and by purified 3beta,17beta-HSD from Pseudomonas testosteroni. In addition to the bacterial 3beta,17beta-HSD the 17beta-HSD of the filamentous fungus Cochliobolus lunatus is the only microbial 17beta-HSD that has been expressed as a recombinant protein and fully characterized. On the basis of its modeled 3D structure, we selected several positions for the replacement of amino acids by site-directed mutagenesis to change substrate specificity, alter coenzyme requirements, and improve overall catalytic activity. Replacement of Val161 and Tyr212 in the substrate-binding region by Gly and Ala, respectively, increased the initial rates for the conversion of androstenedione to testosterone. Replacement of Tyr49 within the coenzyme binding site by Asp changed the coenzyme specificityof the enzyme. This latter mutant can convert the steroids not onlyin the presence of NADP(+) and NADPH, but also in the presence of NADH andNAD(+). The replacement of His164, located in the non-flexible part of the 'lid' covering the active center resulted in a conformation of the enzyme thatpossessed a higher catalytic activity.
    Vir: Journal of biotechnology. - ISSN 0168-1656 (Letn. 129, št. 1, 2007, str. 123-130)
    Vrsta gradiva - članek, sestavni del
    Leto - 2007
    Jezik - angleški
    COBISS.SI-ID - 22003673
vir: Journal of biotechnology. - ISSN 0168-1656 (Letn. 129, št. 1, 2007, str. 123-130)
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