大鼠肾脏中的一种可溶性5'-核苷酸酶。十钒酸盐的刺激作用。
A soluble 5'-nucleotidase in rat kidney. Stimulation by decavanadate.
作者信息
Le Hir M
机构信息
Departement Forschung, Kantonsspital, Basel, Switzerland.
出版信息
Biochem J. 1991 Feb 1;273 ( Pt 3)(Pt 3):795-8. doi: 10.1042/bj2730795.
A soluble 5'-nucleotidase was identified in rat kidney and partially purified. Compared with 5'-IMP, 5'-AMP was a poor substrate. The affinity for 5'-IMP was very low (S0.5 greater than 1 mM) in the absence of an activator, and it was much increased (S0.5 = 0.1 mM) by 2,3-bisphosphoglycerate (2,3-DPG). ATP and bisadenosyl tetraphosphate were further activators. The pH optimum was 6.3. Those properties suggest that the renal soluble 5'-nucleotidase is identical with the 'high-Km' 5'-nucleotidase purified previously from liver, heart and erythrocytes. Decavanadate (100 nM) increased the rate of hydrolysis of 1 mM-5'-IMP 16-fold. The effect was specific for the decameric form of vanadate, since it was not reproduced by either decavanadate-free orthovanadate or pervanadate. Half-maximal activation was obtained at 1.4 nM-decavanadate. Decavanadate increased the affinity of the soluble 5'-nucleotidase for 5'-IMP. The effects of 2,3-DPG and of vanadate were not additive. Thus decavanadate probably influences the soluble 5'-nucleotidase in the same way as 2,3-DPG, but with a much higher potency.
在大鼠肾脏中鉴定出一种可溶性5'-核苷酸酶，并对其进行了部分纯化。与5'-肌苷酸（5'-IMP）相比，5'-腺苷酸（5'-AMP）是一种较差的底物。在没有激活剂的情况下，该酶对5'-IMP的亲和力非常低（半最大底物浓度[S0.5]大于1 mM），而2,3-二磷酸甘油酸（2,3-DPG）可使其亲和力大幅增加（S0.5 = 0.1 mM）。ATP和双腺苷四磷酸是另外的激活剂。最适pH为6.3。这些特性表明，肾脏可溶性5'-核苷酸酶与先前从肝脏、心脏和红细胞中纯化的“高Km”5'-核苷酸酶相同。十钒酸盐（100 nM）使1 mM 5'-IMP的水解速率提高了16倍。该效应具有钒酸盐十聚体形式特异性，因为无十钒酸盐的原钒酸盐或过钒酸盐均未重现此效应。在1.4 nM十钒酸盐时可获得半数最大激活效果。十钒酸盐增加了可溶性5'-核苷酸酶对5'-IMP的亲和力。2,3-DPG和钒酸盐的作用并非相加性的。因此，十钒酸盐可能与2,3-DPG以相同方式影响可溶性5'-核苷酸酶，但效力要高得多。
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