MODEL-CALCULATIONS ON THE AMIDE-I INFRARED BANDS OF GLOBULAR-PROTEINS
MODEL-CALCULATIONS ON THE AMIDE-I INFRARED BANDS OF GLOBULAR-PROTEINS
复制标题
DOI：
10.1063/1.461939
复制
发表时间：
1992-03-01
影响因子：
4.4
通讯作者：
TASUMI, M
中科院分区：
文献类型：
--
作者：
TORII, H;TASUMI, M
通过为每个肽组分配一个具有跃迁偶极的振子，对球状蛋白质的酰胺-I红外（ir）带进行模型计算。 这些振子之间的耦合是通过跃迁偶极耦合机制引入的。 作为模型的应用实例，计算了八种代表性蛋白质的酰胺-I区的红外光谱，计算碳单氧肌红蛋白、核糖核酸酶A、α-乳白蛋白、溶菌酶、黄素氧还蛋白、羧肽酶A、伴刀豆球蛋白A和β-胰蛋白酶。 良好的协议之间获得的计算和观察到的酰胺-I带信封。 在模型计算的基础上讨论了一些结构-光谱相关性。 肌红蛋白在1640 cm-1以下区域出现红外强度显著的谱带，这与其x射线结构不含β折叠相一致。 分析β-折叠对酰胺-I带包络的贡献表明，平行、反平行和混合平行/反平行β-折叠在低于1650 cm-1的波数区域的相似位置产生强红外带，而在高于1650 cm-1的区域没有带可以被视为反平行β-折叠的可靠标记。 非α-非β-部分的贡献分布在一个很宽的波数区域。 α-乳清蛋白和溶菌酶之间的酰胺-I带信封的差异最可能源于这些蛋白质的N末端附近的α-螺旋部分之间的结构差异。
Model calculations are performed on the amide-I infrared (ir) bands of globular proteins by assigning one oscillator with a transition dipole to each peptide group. Coupling between these oscillators is introduced through the transition dipole coupling mechanism. As examples of application of the model, the ir spectra in the amide-I region of eight representative proteins, viz., carbonmonoxy myoglobin, ribonuclease A, alpha-lactalbumin, lysozyme, flavodoxin, carboxypeptidase A, concanavalin A, and beta-trypsin are calculated. Good agreement is obtained between the calculated and observed amide-I band envelopes. Some structure-spectrum correlations are discussed on the basis of the model calculations. The presence of bands with significant ir intensities for myoglobin in the region below 1640 cm-1 is consistent with its x-ray structure having no beta-sheet. Analysis of the contributions of beta-sheets to the amide-I band envelopes shows that parallel, antiparallel, and mixed parallel/antiparallel beta-sheets give rise to strong ir bands at a similar position in the wave number region below 1650 cm-1, and that no band in the region above 1650 cm-1 can be regarded as a reliable marker of antiparallel beta-sheets. The contributions of non-alpha-non-beta-parts spread over a wide wave number region. The differences in the amide-I band envelopes between alpha-lactalbumin and lysozyme originate most probably from the structural differences between the alpha-helical parts near the N termini of these proteins.