- Purification and Characterization of Dehydroascorbate Reductase from Pleurotus ostreatus
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Kim, Yeon Ran , Kang, Sa Ouk
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J. Microbiol. 1998;36(3):164-170.
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Dehydroascorbate reductase was purified 93-fold relative to the crude cell extracts from the cytosolic fraction of the mycelia of Pleurotus ostreatus with an overall yield of 5%. The molecular mass of the native enzyme determined by gel filtration chromatography was 86 kDa. Sodium dodecylsulfate-polyacrylamide gel electrophoresis revealed that the enzyme is a single polypeptide. Dehydroascorbate kreductase from P. ostreatus contained relatively quite a lot of lysine and a relatively small amount of glutamate/glutamine. The enzyme was optimally active at pH 7.5 and at 45℃. Apparent K_m values of dehydroascorbate reductase were 2.5 mM and 0.7 mM for dehydroascorbate and glutathione. The enzyme was significantly unstable under acidic and highly alkaline conditions. The absorption spectrum of the purified enzyme showed an unusual flavin peak, the result of which suggests that the enzyme might form flavin adduct.
- Numerical classification of actinomycetes isolated from volcanic soil
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Kim, Seung Bum , Lee, Soon Dong , Kim, Seon Young , Oh, Hyung Myung , Kang, Sa Ouk , Hah, Yung Chil
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J. Microbiol. 1996;34(2):105-116.
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Of actinomycetes isolated from volcanic compost soils, 115 representative strains which showed distinctive morphologicla features were numerically classified, compared with reference strains of Streptomyces. One hundred and twenty unit characters were tested and the average probability of error was 4.27%. The cluster analysis resulted in two groups: group A included strains of actinomycetes except streptomycetes. Group A was divided into 2 major clusters (over 5 strains), 10-diaminopimelic acid. Group B was divided into 5 clusters, of which 4 clusters contained mesodiminopimelic acid and 1 cluster LL-diaminopimelic acid. The major clusters of group A showed higher abilities of substrate utilization and degradation, and higher resistance to inhibitors, whereas the minor and single member clusters of group A showed relatively higher antimicrobial activities. On the other hand, all clusters of group B showed relatively lower abilities of substrate utilization and degradation and lower resistance to inhibitors.
- Detection of L-xylosone and its physiological effects in saccharomyces cerevisiae
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Seok, Yeong Jae , Yang, Kap Seok , Kang, Ju Gyeong , Kim, Seong Tae , Huh, Won Ki , Kang, Sa Ouk
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J. Microbiol. 1996;34(2):192-197.
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L-Xylosone was detected as its quinoxaline derivative in the degradation solution of dehydro-L-ascorbic acid. The production rate of L-xylosone was much faster in aerated phosphate-cirate buffer (pH 5. 6) than in pure water. L-Xylosone and dehydro-L-ascorbic acid were identified in the crude extracts of Saccharomyces cerevisiae. The concentration of L-xylosone in the crude cell extracts was calculated to be about 0.2 nmol (mg protein)^-1. When L-xylosone was added to asynchronous culture of S. cerevisiae, it inhibited primarily the synthesis of protein and RNA. Examination of the effect of L- xylosone on synchronous culture of the yeast indicated that L-xylosone inhibited the initiation of DNA replication and that the cells were arrested at G₁stage of cell division cycle. These results suggested a possibility that L-xylosone can act as an inhibitor of cell growth.
- An FMN-containing NADH-quinone reductase from streptomyces sp
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Youn, Hong Duk , Lee, Jin Won , Youn, Hwan , Lee, Jeong Kug , Hah, Yung Chil , Kang, Sa Ouk
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J. Microbiol. 1996;34(2):206-213.
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NADH-quinone reductase was purified 22-fold from the cytosolic fraction of Streptomyces sp. Imsnu-1 to apparent hemogenity, with an overall yield of 9%, by the purification procedure consisting of ammonium, sulfate precipitation and DEAE Sephacryl S-200 and DEAE 5 PW chromatographies. The molecular mass of the enzyme determined by gel filtration chromatography was found to be 110 kDa. SDS-PAGE revealed that the enzyme consists of two sugunits with a molecular mass of 54 kDa. The enzyme contained 1 mol of FMN per subunit as a cofactor. The A_272/A_457 ratio was 6.14 and the molar extinction coefficients were calculated to be 20, 800 and 25, 400M/sup -1/cm/sup -1/ AT 349 AND 457 nm, respectively. The N-terminal sequence of the enzyme contained the highly conserved fingerprint of ADP-binding domain. The enzyme used NADH as an electron donor and various quinones as electron acceptors. Cytochrome c was practically inactive. Air-stable flavin semiquinone was produced by the addition of NADH to the enzyme. Also, naphthosemiquinone was detected in the reaction mixture containing the enzyme.
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