Characterization of Porphobilinogen Synthase from an Aerobic Photosynthetic Bacterium, Erythrobacter sp. Strain OCh 114 |
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Authors: | Shioi Yuzo; Doi Michio |
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Institution: | Division of Biology, Miyazaki Medical College Kiyotake, Miyazaki 889-16, Japan |
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Abstract: | Porphobilinogen synthase (formerly 5-aminolevulinic acid dehydratase,EC 4.2.1.24
EC]
) was purified 7,405-fold from an aerobic photosyntheticbacterium, Erythrobacter sp. strain OCh 114. The molecular weightof the enzyme was determined to be 260,000 by Sephadex G-200gel filtration. The enzyme had a single pH optimum at 8.0 andshowed no requirement for metal ion and thiol compound for itsmaximum activity. The Km value for 5-aminolevulinic acid was0.29 mM. 4,5-Dioxovaleric acid and levulinic acid were foundto be competitive inhibitors of the enzyme, with Ki values of0.65 and 0.80 mM, respectively. The enzyme was extremely labilein acidic pH and almost completely lost its activity within1 h at pH 6.0 and 30?C. This Erythrobacter enzyme seems to besimilar to the enzyme from the anaerobic photosynthetic bacteriumRhodobacter capsulatus in its molecular and catalytic properties. (Received February 17, 1988; Accepted May 9, 1988) |
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