Cercignani G
Ital J Biochem. 1982 Jul-Aug;31(4):243-52.
The substrate specificity of two adenosine metabolizing enzymes from Bacillus cereus has been investigated, using partially purified preparations. Adenosine deaminase is shown to be highly specific for adenosine (Km = 5.6 X 10(-5) M at pH 8.1); 2'-deoxyadenosine, formycin A and 2-amino-adenosine are deaminated by the enzyme preparation, but reaction rates are at least 20 times lower than that for adenosine at concentrations up to 0.1 mM, due to higher Km and/or lower Vmax values. 3'-deoxyadenosine is not attacked. Adenosine phosphorylase, on the other hand, can readily act on adenosine, 2'-deoxyadenosine, 2-amino-adenosine and N6-monoalkyl-adenosines; again, 3'-deoxyadenosine shows no appreciable activity as a substrate. The results obtained are briefly discussed, in relation also to current investigations on purine metabolism in vegetative forms and spores of B. cereus.
利用部分纯化的制剂，对蜡样芽孢杆菌的两种腺苷代谢酶的底物特异性进行了研究。腺苷脱氨酶对腺苷具有高度特异性（在pH 8.1时，Km = 5.6×10⁻⁵ M）；2'-脱氧腺苷、间型霉素A和2-氨基腺苷可被该酶制剂脱氨，但在浓度高达0.1 mM时，由于较高的Km值和/或较低的Vmax值，反应速率至少比腺苷低20倍。3'-脱氧腺苷不被作用。另一方面，腺苷磷酸化酶可轻易作用于腺苷、2'-脱氧腺苷、2-氨基腺苷和N⁶-单烷基腺苷；同样，3'-脱氧腺苷作为底物没有明显活性。还结合目前对蜡样芽孢杆菌营养体和孢子中嘌呤代谢的研究，简要讨论了所得结果。
