Chartier François J M, Couture Manon
Département de Biochimie et de Microbiologie, and Centre de Recherche sur la fonction, la structure et l'ingénierie des protéines (CREFSIP), Université Laval, Québec, Canada.
Biochem J. 2007 Jan 1;401(1):235-45. doi: 10.1042/BJ20060913.
We report here the resonance Raman spectra of the FeIII-NO and FeII-NO complexes of the bacterial NOSs (nitric oxide synthases) from Staphylococcus aureus and Bacillus subtilis. The haem-NO complexes of these bacterial NOSs displayed Fe-N-O frequencies similar to those of the mammalian NOSs, in presence and absence of L-arginine, indicating that haem-bound NO and L-arginine had similar haem environments in bacterial and mammalian NOSs. The only notable difference between the two types of NOS was the lack of change in Fe-N-O frequencies of the FeIII-NO complexes upon (6R) 5,6,7,8-tetrahydro-L-biopterin binding to bacterial NOSs. We report, for the first time, the characterization of NO complexes with NOHA (N(omega)-hydroxy-L-arginine), the substrate used in the second half of the catalytic cycle of NOSs. In the FeIII-NO complexes, both L-arginine and NOHA induced the Fe-N-O bending mode at nearly the same frequency as a result of a steric interaction between the substrates and the haem-bound NO. However, in the FeII-NO complexes, the Fe-N-O bending mode was not observed and the nu(Fe-NO) mode displayed a 5 cm(-1) higher frequency in the complex with NOHA than in the complex with L-arginine as a result of direct interactions that probably involve hydrogen bonds. The different behaviour of the substrates in the FeII-NO complexes thus reveal that the interactions between haem-bound NO and the substrates are finely tuned by the geometry of the Fe-ligand structure and are relevant to the use of the FeII-NO complex as a model of the oxygenated complex of NOSs.
我们在此报告了来自金黄色葡萄球菌和枯草芽孢杆菌的细菌一氧化氮合酶（NOSs）的FeIII-NO和FeII-NO配合物的共振拉曼光谱。在有和没有L-精氨酸存在的情况下，这些细菌NOSs的血红素-NO配合物显示出与哺乳动物NOSs相似的Fe-N-O频率，这表明在细菌和哺乳动物NOSs中，血红素结合的NO和L-精氨酸具有相似的血红素环境。这两种类型的NOS之间唯一显著的差异是，当(6R) 5,6,7,8-四氢-L-生物蝶呤与细菌NOSs结合时，FeIII-NO配合物的Fe-N-O频率没有变化。我们首次报道了与NOHA（N(ω)-羟基-L-精氨酸）形成的NO配合物的表征，NOHA是NOSs催化循环后半段所使用的底物。在FeIII-NO配合物中，由于底物与血红素结合的NO之间的空间相互作用，L-精氨酸和NOHA均以几乎相同的频率诱导Fe-N-O弯曲模式。然而，在FeII-NO配合物中，未观察到Fe-N-O弯曲模式，并且由于可能涉及氢键的直接相互作用，与NOHA形成的配合物中的ν(Fe-NO)模式比与L-精氨酸形成的配合物中的频率高5 cm(-1)。因此，FeII-NO配合物中底物的不同行为表明，血红素结合的NO与底物之间的相互作用通过Fe-配体结构的几何形状进行了精细调节，并且与将FeII-NO配合物用作NOSs氧化配合物的模型相关。
