Characterization of 5-Aminolevulinic Acid Dehydratase Purified from Anabaena cylindrica
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In Cheol Lee, Soon-Ae Yoo
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Department of Biology, Taejon University, Department of Biology, Paichai University
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ABSTRACT |
A 5-aminolevulinic acid dehydratase (ALAD, E.C.4.2.1.24) was purified and characterized from Anabaena cylindrica (IAM-1). The enzyme was purified about 140 fold by ammonium sulfate precipitation, ion exchange chromatography, gel filtration and Toyo-pearl LC chromatography. The native size of the enzyme was approximate 420 kDa as judge by gel filtration and native polyacrylamide gel electrophoresis. By the SDS-PAGE, the protein was found to be composed with identical subunits of molecular weight of 43 kDa. The Km for 5-aminolevulinic acid was 1.2 mM in the presence of 5 mM MgCl sub(2) and 5 mM β-mercaptoethanol. ALAD activity was reduced significantly by the dialysis against buffer containing EDTA or by the treatment of chelex cation exchanger. The chelex-treated ALAD activity was recovered by the addition of magnesium ion. On the contrast, the addition of 3 mM ZnCl sub(2) to the chelex treated ALAD caused the inhibition of enzyme activity by 90%. The inhibition, however, was partially overcome by 10 mM MgCl sub(2). These results suggested the Mg-dependent ALAD be the prominent one in A. cylindrica.
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Key words:
Anabaena cylindrica, 5-Aminolevulic acid dehydratase, metal requirement |
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