- Purification and Characterization of NADPH-Dependent Cr(VI) Reductase from Escherichia coli ATCC 33456
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Woo-Chul Bae , Han-Ki Lee , Young-Chool Choe , Deok-Jin Jahng , Sang-Hee Lee , Sang-Jin Kim , Jung-Hyun Lee , Byeong-Chul Jeong
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J. Microbiol. 2005;43(1):21-27.
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DOI: https://doi.org/2143 [pii]
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 Abstract
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A soluble Cr(VI) reductase was purified from the cytoplasm of Escherichia coli ATCC 33456. The molecular mass was estimated to be 84 and 42 kDa by gel filtration and SDS-polyacrylamide gel electrophoresis, respectively, indicating a dimeric structure. The pI was 4.66, and optimal enzyme activity was obtained at pH 6.5 and 37^oC. The most stable condition existed at pH 7.0. The purified enzyme used both NADPH and NADH as electron donors for Cr(VI) reduction, while NADPH was the better, conferring 61% higher activity than NADH. The K_m values for NADPH and NADH were determined to be 47.5 and 17.2 umol, and the V_max values 322.2 and 130.7 umol Cr(VI) min^-1mg^-1 protein, respectively. The activity was strongly inhibited by N-ethylmalemide, Ag^2+, Cd^2+, Hg^2+, and Zn^2+. The antibody against the enzyme showed no immunological cross reaction with those of other Cr(VI) reducing strains.
- Purification and Characterization of Cold Active Lipase from Psychrotrophic Aeromonas sp. LPB 4
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Han-Ki Lee , Min-Jung Ahn , Sung-Ho Kwak , Won-Ho Song , Byeong-Chul Jeong
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J. Microbiol. 2003;41(1):22-27.
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Abstract
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A lipase from Aeromonas sp. LPB 4, a psychrotophile isolated from a sea sediment was purified and characterized. The lipase was purified 53.5 fold to a homogeneous state by acetone precipitation and QAE sephadex column chromatography and its molecular weight was determined to be 50 kDa by SDS-PAGE. The enzyme exhibited maximum activity at 10oC and was stable at temperatures lower than 50℃. This lipase favored substrates containing medium carbon chain of acyl group, while too low and high carbon chain decreased its activity. The lipolytic activity of purified lipase was slightly increased by the addition of 0.1% detergent, but decreased by 1% of detergent. Butanol severely decreased the lipase activity while methanol increased the activity about 15%.
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