Jarzecki Andrzej A
Department of Chemistry, Brooklyn College and the Graduate School of the City University of New York, Brooklyn, New York 11210, USA.
J Phys Chem A. 2009 Mar 26;113(12):2926-34. doi: 10.1021/jp8095715.
A framework of the weighted-gradient approach is developed for effective quantum-mechanical modeling of resonance Raman (RR) intensities with a view toward rationalizing enhancement patterns observed for histidine and tryptophan side chains. Unlike the single-state gradient approach, this new procedure utilizes the vertical gradients obtained for all computed excited states to produce an effective gradient and the RR intensity patterns for a particular frequency of the excitation photon. The dramatic spectral changes observed for the histidine ring upon its protonation, deprotonation, or deuterium substitution of exchangeable protons is well reproduced by this model. Spectral comparison for the tryptophan ring clearly demonstrated improved quality of the weighted-gradient over the single-state gradient approach. Computed spectra exemplify the potential application of this model to support vibrational studies of electronic and structural interactions of chromophores in proteins.
为了合理地解释在组氨酸和色氨酸侧链中观察到的增强模式，开发了一种加权梯度方法的框架，用于对共振拉曼（RR）强度进行有效的量子力学建模。与单态梯度方法不同，这种新方法利用为所有计算出的激发态获得的垂直梯度来产生有效梯度和激发光子特定频率下的RR强度模式。该模型很好地再现了组氨酸环在质子化、去质子化或可交换质子的氘代时观察到的显著光谱变化。色氨酸环的光谱比较清楚地表明，加权梯度方法的质量优于单态梯度方法。计算光谱举例说明了该模型在支持蛋白质中发色团的电子和结构相互作用的振动研究方面的潜在应用。
