Mechanism of YC-1-induced activation of soluble guanylyl cyclase
Mechanism of YC-1-induced activation of soluble guanylyl cyclase
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DOI：
10.1124/mol.53.1.123
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发表时间：
1998-01-01
影响因子：
3.6
通讯作者：
Koesling, D
中科院分区：
文献类型：
--
作者：
Friebe, A;Koesling, D
信号分子一氧化氮（NO）通过刺激可溶性鸟苷酸环化酶（sGC）介导其许多作用。激活过程是由NO与酶的辅血红素基团的高亲和力结合引发的。尽管一氧化碳（GO）的sGC活化特性较差，但其也被认为是sGC的生理活化剂。最近，我们已经表明，物质YC-1，苄基吲唑衍生物，刺激sGC的10倍（独立于NO）增强NO的刺激作用，并把CO变成一个有效的激活sGC。在本研究中，我们表明，激活sGC的原卟啉IX，配体非依赖性激活剂，是由YC-1增强，但没有观察到的浓度-响应曲线的位移与NO和CO。YC-1减缓了NO和CO从活化酶的解离速率，如通过添加NO和CO清除剂氧合血红蛋白后cGMP积累所监测的。可以排除YC-1与血红素基团的直接相互作用，因为YC-1不改变基础或刺激的sGC的Soret吸收，此外，仍然与血红素耗尽的酶结合。总之，我们的研究结果表明，YC-1增加了最大催化速率，并通过结合到sGC分子上的变构位点使酶对其气体活化剂敏感，从而降低了血红素基团的配体解离速率。
The signaling molecule nitric oxide (NO) mediates many of its effects by the stimulation of soluble guanylyl cyclase (sGC). The activation process is initiated by high-affinity binding of NO to the enzyme's prosthetic heme group. Despite its poor sGC-activating properties, carbon monoxide (GO) has also been suggested as a physiological activator of sGC. Recently, we have shown that the substance YC-1, a benzyl indazole derivative, stimulates sGC by 10-fold (independently of NO) potentiates the stimulatory effect of NO, and turns CO into a potent activator of sGC. In the present study, we show that activation of sGC by protoporphyrin IX, a ligand-independent activator, was potentiated by YC-1, yet a shift of the concentration-response curve as seen with NO and CO was not observed. YC-1 slowed down the dissociation rates for NO and CO from the activated enzyme as monitored by cGMP accumulation after addition of the NO and CO scavenger oxyhemoglobin. A direct interaction of YC-1 with the heme group can be ruled out because YC-1 did not change the Soret absorption of basal or stimulated sGC and, in addition, still bound to the heme-depleted enzyme. Together, our results indicate that YC-1 increases the maximal catalytic rate and sensitizes the enzyme toward its gaseous activators by binding to an allosteric site on sGC molecules, thereby reducing the ligand dissociation rate from the heme group.