Some Properties of Xanthine Dehydrogenase from Pseudomonas synuantha A3

Pseudomonas synxantha A3에서 분리한 Xanthine Dehydrogenase의 성질

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.

Pseudomonas synxantha A3으로부터 정제된 결정화 효소를 사용하여 몇가지의 성질을 검토하였다. 본 효소에 대한 nucleoside 관련물질의 저해관계를 검토한 결과, 그 중에서 adenine, 8-azaadenine, 2-methyladenine, guanine, 8-azaguanine에 의해서 강한 저해를 받는 것으로 나타났으며, caffenine에 의해서는 저해를 받지 않았다. Adenine과 guanine은 비길항저해제로서, 그 저해상수($K_i$)는 각각 0.037mM과 0.098mM 이었다.