Branched Chain Amino Acid Aminotransferase of Pseudomonas sp |
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Authors: | Yuji Koide Mamoru Honma Tokuji Shimomura |
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Affiliation: | Department of Agricultural Chemistry, Faculty of Agriculture, Hokkaido University, Sapporo, Japan |
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Abstract: | Branched chain amino acid aminotransferase was partially purified from Pseudomonas sp. by ammonium sulfate fractionation, aminohexyl-agarose and Bio-Gel A-0.5 m column chromatography.This enzyme showed different substrate specificity from those of other origins, namely lower reactivity for l-isoleucine and higher reactivity for l-methionine.Km values at pH 8.0 were calculated to be 0.3 mm for l-leucine, 0.3 mm for α-ketoglutarate, 1.1 mm for α-ketoisocaproate and 3.2 mm for l-glutamate.This enzyme was activated with β-mercaptoethanol, and this activated enzyme had different kinetic properties from unactivated enzyme, namely, Km values at pH 8.0 were calculated to be 1.2 mm for l-leucine, 0.3 mm for α-ketoglutarate.Isocaproic acid which is the substrate analog of l-leucine was competitive inhibitor for pyridoxal form of unactivated and activated enzymes, and inhibitor constants were estimated to be 6 mm and 14 mm, respectively. |
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Keywords: | squalene oxidosqualene squalene-hopene cyclase QW motifs Alicyclobacillus acidocaldarius |
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