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Accession number;04A0258632
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| Title;Restore of alkaliphily of a mutant alkaline xylanase with an acidic pH optimum. |
| Author;
INAMI MAYUKO
(Tokyo Inst. of Technology, Graduate School)
MOROKUMA CHIHIRO
(Tokyo Inst. of Technology, Graduate School)
SUGIO AKIKO
(Tokyo Inst. of Technology, Graduate School)
TAMANOI HIDENORI
(Tokyo Inst. of Technology, Graduate School)
YATSUNAMI RIE
(Tokyo Inst. of Technology, Graduate School)
NAKAMURA SATOSHI
(Tokyo Inst. of Technology, Graduate School)
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Journal Title;Abstracts. Symposium on Biofunctional Chemistry
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Journal Code:L0836A
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ISSN:
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VOL.18th;NO.;PAGE.100-101(2003)
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| Figure&Table&Reference;FIG.1, REF.3 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Xylanase J (XynJ) from alkaliphilic Bacillus sp. strain 41M-1 has an alkaline pH optimum and is composed of a family 11 catalytic domain and a xylan-binding domain (XBD). Many XynJ mutants with acidic and neutral pH optima have previously been obtained by a single amino acid substitution in the catalytic domain. Of all the mutants, mutant E177Q (Glu177 is substituted by Gln) is the most acidophilic one with a pH optimum of 5.0. In this study, we shifted the pH optimum of mutant E177Q to the alkaline side as a first step of creating more alkaline-active XynJ mutants by the supressor mutation procedure. E177Q.DELTA.JC lacking the XBD had an acidic pH optimum and showed almost no activity at pH 8.0 just like E177Q composed of the catalytic domain and XBD. The alkaliphily of the enzyme was restored by directed evolution. The evolved mutants, Y176S/E177Q.DELTA.JC and G32V/Y176D/E177Q.DELTA.JC, retained about 30% and 43% activity of their maximal activities at pH 6.0, respectively. (author abst.) |
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