NMR、IR/Raman 和 HNO 和 RNO（R = 烷基和芳基）金属卟啉的结构性质及其对 HNO-肌红蛋白复合物的影响。
NMR, IR/Raman, and structural properties in HNO and RNO (R = alkyl and aryl) metalloporphyrins with implication for the HNO-myoglobin complex.
机构信息
Department of Chemistry and Biochemistry, University of Southern Mississippi, 118 College Drive #5043, Hattiesburg, Mississippi 39406, USA.
出版信息
J Am Chem Soc. 2010 Feb 10;132(5):1583-91. doi: 10.1021/ja907342s.
Structural and functional details of heme protein complexes with HNO and the isoelectronic RNO (R = alkyl and aryl) molecules (metabolic intermediates) are largely unknown. We report a quantum chemical investigation of three characteristic spectroscopic properties, (1)H and (15)N NMR chemical shifts and NO vibrational frequencies in synthetic HNO and RNO heme complexes, with theory-versus-experiment correlation coefficients R(2) = 0.990-0.998. A new density functional theory (DFT) method was found to yield excellent predictions of experimental structures of HNO, RNO, and NO heme systems. Interestingly, this method also helps the identification of an excellent linear quantitative structure observable relationship between NO vibrational frequencies and bond lengths in all of these NO-containing systems. This suggests that NO vibrations are largely local effects of the NO bonds in these complexes and may help deduce the NO bond lengths from using experimental vibrational data in these systems. The NO vibrational frequencies in HNO, RNO, and NO metalloporphyrins were found to follow a general trend of NO > RNO > HNO complexes, as a result of the electron populations in the antibonding NO orbitals of NO < RNO < HNO complexes. Investigations of the NMR and IR/Raman spectroscopic data in HNO metal complexes show that HNO is a strong pi-acid. In addition, we performed the first quantum chemical investigation of the hydrogen-bond effect on HNO in MbHNO (Mb = myoglobin) models. On the basis of comparisons with experimental (1)H and (15)N NMR results and NO vibrational frequency in MbHNO, a dual hydrogen-bond mode for HNO in MbHNO was proposed. The enhanced stability from this dual hydrogen bonding may provide a basis for the unusual stability of MbHNO observed experimentally. These results should facilitate spectroscopic characterizations and structural investigations of HNO and RNO heme proteins and models.
血红素蛋白与 HNO 和等电子体 RNO（R = 烷基和芳基）（代谢中间体）复合物的结构和功能细节在很大程度上尚不清楚。我们报告了对三种特征光谱性质的量子化学研究，即（1）H 和（15）N NMR 化学位移和 NO 振动频率在合成 HNO 和 RNO 血红素配合物中的变化，理论与实验相关系数 R（2）= 0.990-0.998。发现一种新的密度泛函理论（DFT）方法可以很好地预测 HNO、RNO 和 NO 血红素体系的实验结构。有趣的是，该方法还有助于识别这些含 NO 体系中 NO 振动频率与键长之间的优异线性定量结构可观察性关系。这表明 NO 振动在很大程度上是这些配合物中 NO 键的局部效应，并可能有助于从这些体系的实验振动数据中推断出 NO 键长。在 HNO、RNO 和 NO 金属卟啉中，NO 振动频率呈现出一般趋势，即 NO > RNO > HNO 配合物，这是由于 NO 配合物中反键 NO 轨道上的电子密度 NO < RNO < HNO。对 HNO 金属配合物中 NMR 和 IR/Raman 光谱数据的研究表明，HNO 是一种强π酸。此外，我们首次对 MbHNO（Mb = 肌红蛋白）模型中 HNO 的氢键效应进行了量子化学研究。根据与 MbHNO 中实验（1）H 和（15）N NMR 结果和 NO 振动频率的比较，提出了 MbHNO 中 HNO 的双重氢键模式。这种双重氢键的增强稳定性可能为实验中观察到的 MbHNO 的异常稳定性提供了基础。这些结果应该有助于 HNO 和 RNO 血红素蛋白和模型的光谱特征和结构研究。
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