http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
소재현,김원찬,신재호,Choon-Bal Yu,이인구 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.5
A β-glucosidase, efficiently hydrolyzing isoflavone glycoside to isoflavone aglycone, was purified from Pichia guilliermondii K123-1, isolated from Korean soybean paste by ammonium sulfate precipitation, ion exchange column chromatography, gel filtration, and fast protein liquid chromatogram (FPLC). The molecular mass of purified enzyme was estimated to be 45 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDSPAGE). The optimum temperature for enzyme activity was 45℃ and it decreased dramatically above 50℃. The maximal activity was at pH 4.5 and more than 80% of the activity was retained for 24 hr in the pH range from 4.0 to 8.0 at 4℃. The N-terminal amino acid sequence of the enzyme was determined to be GLNWDYDNDK. Based on its substrate specificity and catalytic properties, the activity of the purified β-glucosidase was more effective when the sugar moiety of the glycoside was glucose and the size of the aglycone similar to that of the isoflavones. The purified β-glucosidase efficiently converts genistin and daidzin to genistein and daidzein 1.96 and 1.75 times more than almond meal β-glucosidase.
Cloning and Characterization of a Cyclohexanone Monooxygenase Gene from Arthrobacter sp. L661
김영목,정용현,Soon-Hyun Jung,Choon-Bal Yu,이인구 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.1
Cyclohexanone monooxygenase (CHMO), a type of Baeyer-Villiger oxidation, catalyzes the oxidation of cyclohexanone into ε-caprolactone, which has been utilized as a building block in organic synthesis. A bacterium that is capable of growth on cyclohexanone as a sole carbon source was recently isolated and was identified as Arthrobacter sp. L661. The strain is believed to harbor a CHMO gene (chnB), considering the high degradablity of cyclohexanone. In order to characterize the CHMO, a chnB gene was cloned from Arthrobacter sp. L661. The deduced amino acids of the chnB gene evidenced the highest degree of homology (90% identity) with the CHMO of Arthrobacter sp. BP2 (accession no. AY123972). The CHMO of L661 was shown to be functionally expressed in Escherichia coli cells, purified via affinity chromatography, and characterized. The specific activity of the purified enzyme was 24.75 μmol/min/mg protein. The optimum pH was 7.0 and the enzyme maintained over 70% of its activity for up to 24 h in a pH range of 6.0 to 8.0 at 4℃. The CHMO of L661 readily oxidized cyclobutanone and cyclopentanone whereas less activity was detected with those of Arthrobacter sp. BP2, Rhodococcus sp. Phi1, and Rhodococcus sp. Phi2, thereby suggesting that the CHMO of L661 evidenced the different substrate specificities compared with other CHMOs. These results can provide us with useful information for the development of biocatalysts applicable to commercial organic syntheses, especially because only a few CHMO genes have been identified thus far.