• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.610-613
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• 1991

Some of the Kinetic properties of crystallic xanthine dehydrogenase form Pseudomonas synxantha A3 were studied. The enzyme activity was strongly inhibited by adenine, 8-azaadenine, 2-methyladenine, guanine, and 8-azaguanine, but not by caffeine, and the inhibitions by adenine and guanine were observed to be of noncompetitive type. The $K_i$ values for adenine and guanine were 0.037 and 0.098 mM, respectively. Michaelis constants were found to be 0.33 and 0.06 rnM for hypoxanthine and xanthine with $NAD^+$ as the second substrate, respectively, and 0.1 rnM for $NAD^+$ with either hypoxanthine or xanthine as the second substrate.

• Korean Journal of Microbiology
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• v.29 no.5
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• pp.307-313
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• 1991

A yellow-green, fluorescent siderophore A3 was extracellularly produced under iron-limited growth conditions from Pseudomonas synxantha A3. The physicochemical and biological properties of siderophore A3 were examined. The approxiamte molecular weights of the Fe(III)-siderophore A3-1 complex and Fe(III)-siderophore A3-2 complex were estimated to be about 1,300 and 1,100, respectively, by Bio-gel P2 gel exclusion chromatography. The molar ratio between the siderophore and the Fe(III)was 1.08 mole. The molecular weight of the complex could be calculated with this ratio and the new values were 1,150 and 960, respectively. The binding constant(K) between thesiderophore A3 and Fe(III) that determined by displacing the iron from the Fe(III)-siderophore complex with EDTA was 4.12*10$^{18}$ at pH 5.0. Siderophore A3 appeared to have antibacterial activity on several bacterial strains, however, ferric siderophore Ae complex did not show that activity. The cytotoxicity of siderophore A3 was obtained from Human Chronic Myelogenous Leudemia K562 cells. Inhibition concentration (50%)($IC_{50}$ ) was $0.17\mu$\{g/ml}.

• Microbiology and Biotechnology Letters
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• v.14 no.6
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• pp.441-446
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• 1986

Some properties of extracellular guanine deaminase produced by Pseudomonas synxantha A3 were studied. The enzyme was stable at pH 6.5-7.5 and generally stable when it was incubated at 4$0^{\circ}C$ for 10 minutes but inactivated gradually above 4$0^{\circ}C$. When the enzyme in 0.2M potassium phosphate (pH 8.0) was stored at room temperature, it was stable for thirty days. Alcohols and acetone were not effective for the eyzyme stability. The optimum pH and temperature for the enzyme activity were around pH 7.0-8.0 and 5$0^{\circ}C$, respectively. The enzyme was inhibited by 1mM of Hg$^{++}$, Ag$^+$ and Li$^+$ and by 0.1mM of Ag$^+$ with about 50% loss of activity. The enzyme inhibited by Li$^+$ was reactivated by EDTA. 1 mM of pentachlorophenol and p-CMB inactivated the enzyme with 50% and 40% loss of activity, respectively. The enzyme inactivated by p-CMB was reactivated by glutathione.