Characterization of two different five-coordinate soluble guanylate cyclase ferrous-nitrosyl complexes
Characterization of two different five-coordinate soluble guanylate cyclase ferrous-nitrosyl complexes
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DOI：
10.1021/bi7022943
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发表时间：
2008-03-25
期刊：
影响因子：
2.9
通讯作者：
Marletta, Michael A.
中科院分区：
文献类型：
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作者：
Derbyshire, Emily R.;Gunn, Alexander;Marletta, Michael A.
可溶性鸟苷环化酶(SGC)是一种血红素蛋白，是高等真核生物中主要的一氧化氮(NO)受体。NO与sGC结合后形成五配位亚铁-亚硝基络合物，cGMP合成增加数百倍。GTP和变构激活剂YC-1和BAY 41-2272对sGC的NO激活有影响。电子顺磁共振(EPR)谱表明，在YC-1、Bay 41-2272或GTP存在下，sGC亚铁-亚硝基络合物的光谱相对于血红素发生移动。这些分子将电子顺磁共振信号从特征为g(1)=2.083、g(2)=2.036和g(3)=2.012的信号转变为特征为g(1)=2.106、g(2)=2.029和g(3)=2.010的信号。将截短的血红素结构域结构β1(1-194)和β2(1-217)与全长酶进行比较。β2(1-2 7)-NO复合体的EPR谱特征为g(1)=2.106，g(2)=2.025，g(3)=2.010，表明在有激活剂存在的情况下，该蛋白质是sGC-NO复合体的良好模型，而在没有激活剂的情况下，β1(1-194)-NO复合体的EPR谱类似于sGC的EPR谱。β1(1-194)-NO和β2(1-217)-NO络合物的低温共振拉曼光谱表明，β2(1-217)-NO络合物的Fe-NO伸缩振动(cm(-1))明显不同于β1(1-194)-NO络合物(527 cm(-1))。这表明sGC可以采用不同的五配位亚硝酸亚铁构象，并表明以这种独特的EPR信号和Fe-NO伸缩振动为特征的Fe-NO构象代表了sGC的高活性状态。
Soluble guanylate cyclase (sGC), a hemoprotein, is the primary nitric oxide (NO) receptor in higher eukaryotes. The binding of NO to sGC leads to the formation of a five-coordinate ferrous-nitrosyl complex and a several hundred-fold increase in cGMP synthesis. NO activation of sGC is influenced by GTP and the allosteric activators YC-1 and BAY 41-2272. Electron paramagnetic resonance (EPR) spectroscopy shows that the spectrum of the sGC ferrous-nitrosyl complex shifts in the presence of YC-1, BAY 41-2272, or GTP in the presence of excess NO relative to the heme. These molecules shift the EPR signal from one characterized by g(1) = 2.083, g(2) = 2.036, and g(3) = 2.012 to a signal characterized by g(1) = 2.106, g(2) = 2.029, and g(3) = 2.010. The truncated heme domain constructs beta 1(1-194) and beta 2(1-217) were compared to the full-length enzyme. The EPR spectrum of the beta 2(1-217)-NO complex is characterized by g(1) = 2.106, g(2) = 2.025, and g(3) = 2.010, indicating the protein is a good model for the sGC-NO complex in the presence of the activators, while the spectrum of the beta 1(1-194)-NO complex resembles the EPR spectrum of sGC in the absence of the activators. Low-temperature resonance Raman spectra of the beta 1(1-194)-NO and beta 2(1-217)-NO complexes show that the Fe-NO stretching vibration of the beta 2(1-217)-NO complex (535 cm(-1)) is significantly different from that of the beta 1(1-194)-NO complex (527 cm(-1)). This shows that sGC can adopt different five-coordinate ferrous nitrosyl conformations and suggests that the Fe-NO conformation characterized by this unique EPR signal and Fe-NO stretching vibration represents a highly active sGC state.