Some Properties of GTP Cyclohydrolase from Serratia indica and the Pterin Product by Its Enzymatic Reaction |
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Authors: | Masahiro Kobashi Hitoshi Hariu Kazuo Iwai |
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Institution: | The Research Institute for Food Science, Kyoto University, Uji, Kyoto 611 |
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Abstract: | GTP cyclohydrolase which catalyzes the formation of formic acid and a pterin compound from guanosine-5′-triphosphate (GTP) has been partially purified from extracts of Serratia indica IFO 3759. 14C-Formic acid eliminated from (8-14C)GTP is oxidized with mercury acetate to 14CO2, which is trapped by β-phenylethylamine. The molecular weight of the enzyme is approximately 170,000 and the enzyme is relatively heat-stable. The enzyme activity is strongly inhibited by GDP and ATP, but not by other nucleotides. Inhibition by GDP is competitive with GTP. Metals, such as Fe2+, Co2+, Ni2+, Zn2+, Cd2+, Al3+, Hg2+ and p-chloromercuribenzoate strongly inhibit the enzyme activity. The activity is also inhibited by d-erythro-neopterin triphosphate prepared from the enzyme system of Escherichia coli B, since (1) only one mole of phosphate can be liberated by alkaline phosphatase and two moles of phosphates by phosphodiesterase and alkaline phosphatase from the product, and (2) the retention time of the product on high-performance liquid chromatography is different from that of d-erythro-neopterin triphosphate. |
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Keywords: | glycolipids biosurfactants cellobiose lipids Cryptococcus humicola |
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