Rendell M S, Rodbell M, Berman M
J Biol Chem. 1977 Nov 25;252(22):7909-12.
A three-state model developed originally from analysis of the steady state kinetics of hepatic adenylate cyclase has been extended to account for the transient kinetics of activation by guanyl-5'-yl imidodiphosphate (Gpp(NH)p). In contrast to activation by Gpp(NH)p, activation of the enzyme by GTP proceeds not only without a lag phase but is of considerably lower magnitude. These differences between Gpp(NH)p and GTP can be explained by the hypothesis that GTP is hydrolyzed at the nucleotide regulatory site(s) associated with adenylate cyclase and that GTPase activity is revealed uniquely when the enzyme system is in its state of highest adenylate cyclase activity. With this hypothesis, the characteristics of activation by GTP could be simulated. The implications of this model are discussed with respect to the actions of hormones and cholera toxin on adenylate cyclase activity.
最初从肝脏腺苷酸环化酶稳态动力学分析发展而来的三态模型已得到扩展，以解释鸟苷 - 5'- 亚氨基二磷酸（Gpp(NH)p）激活的瞬态动力学。与Gpp(NH)p激活不同，GTP对该酶的激活不仅没有滞后阶段，而且幅度要低得多。Gpp(NH)p和GTP之间的这些差异可以通过以下假设来解释：GTP在与腺苷酸环化酶相关的核苷酸调节位点被水解，并且当酶系统处于最高腺苷酸环化酶活性状态时，GTPase活性才会独特地显现出来。基于这一假设，可以模拟GTP激活的特征。本文讨论了该模型对于激素和霍乱毒素对腺苷酸环化酶活性作用的意义。
