Inagaki F, Shimada I
J Inorg Biochem. 1986 Oct-Nov;28(2-3):311-7. doi: 10.1016/0162-0134(86)80095-2.
Hexacyanochromate ion, (Cr(CN)6)3-, was applied to ribonuclease T1 (RNase T1), which specifically cleaves RNA chains at guanylic acid residues. From kinetic studies, this anion was shown to bind to the active site of RNase T1 as a competitive inhibitor. Therefore, the line broadening effect of NMR resonances due to binding of (Cr(CN)6)3- was analyzed for the mapping of the active site of RNase T1. His-40 C2 proton resonance was significantly broadened, following His-92 C2 proton resonance upon binding of (Cr(CN)6)3-, while His-27 C2 proton resonance did not show any appreciable line broadening. Moreover, from the pH dependence of the line broadening effect, the binding of (Cr(CN)6)3- was shown to be controlled by the ionic state of Glu-58. Based on the present NMR results and x-ray crystal structure, the active site structure of RNase T1 is discussed.
六氰基铬酸根离子（Cr(CN)₆³⁻）被应用于核糖核酸酶T1（RNase T1），它能特异性地在鸟苷酸残基处切割RNA链。通过动力学研究表明，这种阴离子作为竞争性抑制剂与RNase T1的活性位点结合。因此，分析了由于（Cr(CN)₆³⁻）结合导致的核磁共振共振线宽效应，以绘制RNase T1的活性位点图谱。在（Cr(CN)₆³⁻）结合后，His-40 C₂质子共振显著变宽，随后是His-92 C₂质子共振，而His-27 C₂质子共振没有显示出任何明显的线宽增加。此外，从线宽效应的pH依赖性来看，（Cr(CN)₆³⁻）的结合受Glu-58离子状态的控制。基于目前的核磁共振结果和X射线晶体结构，对RNase T1的活性位点结构进行了讨论。
