Capito K, Hedeskov C J
Biochem J. 1977 Mar 15;162(3):569-73. doi: 10.1042/bj1620569.
The effects of glucose, a series of glucose metabolites, nicotinamide nucleotides, Ca2+ and p-chloromercuribenzenesulphonate on adenylate cyclase activity in homogenates of mouse pancreatic islets were studied. The basal activity of the adenylate cyclase was approx. 6 pmol of cyclic AMP formed/30 min per microng of DNA at 30 degrees C. The enzyme activity was stimulated by some 150% by fluoride. Starvation of the animals for 48h had no effect on either the basal or the fluoride-stimulated activity. The adenylate cyclase activity was increased by 40-50% when 17 mM-glucose, 10 micronM-phosphoenolpyruvate or 10 micronM-pyruvate was added to the assay medium. The effect of glucose was unchanged in the presence of 17 mM-mannoheptulose, and mannoheptulose alone had no effect. The other glycolytic intermediates, and the coenzymes NAD+, NADH and NADPH, at concentrations up to 1 mM were without any detectable effect on the rate of formation of cyclic AMP. The insulin secretagogue p-chloromercuribenzenesulphonate inhibited the adenylate cyclase markedly even at a concentration of 10 micronM. Calculated concentrations of free Ca2+ of 10 micronM and 0.1 mM inhibited adenylate cyclase by 29 and 71% respectively. It is concluded that both glucose itself and phosphoenolpyruvate and/or pyruvate are true activating ligands for islet and adenylate cyclase and that inhibition of the cyclase by Ca2+ may be of physiological significance.
研究了葡萄糖、一系列葡萄糖代谢产物、烟酰胺核苷酸、Ca2+和对氯汞苯磺酸盐对小鼠胰岛匀浆中腺苷酸环化酶活性的影响。腺苷酸环化酶的基础活性约为在30℃下每微克DNA每30分钟形成6 pmol环磷酸腺苷。该酶活性受到氟化物约150%的刺激。动物饥饿48小时对基础活性或氟化物刺激的活性均无影响。当向测定培养基中加入17 mM -葡萄糖、10 μM -磷酸烯醇丙酮酸或10 μM -丙酮酸时，腺苷酸环化酶活性增加40 - 50%。在存在17 mM -甘露庚酮糖的情况下，葡萄糖的作用不变，且单独的甘露庚酮糖无作用。其他糖酵解中间产物以及浓度高达1 mM的辅酶NAD+、NADH和NADPH对环磷酸腺苷的形成速率没有任何可检测到的影响。胰岛素促分泌剂对氯汞苯磺酸盐即使在10 μM的浓度下也能显著抑制腺苷酸环化酶。计算得出的游离Ca2+浓度为10 μM和0.1 mM时，分别抑制腺苷酸环化酶29%和71%。得出的结论是，葡萄糖本身以及磷酸烯醇丙酮酸和/或丙酮酸都是胰岛腺苷酸环化酶真正的激活配体，并且Ca2+对环化酶的抑制可能具有生理意义。
