Pancoska P, Wang L, Keiderling T A
Department of Chemistry, University of Illinois, Chicago 60680.
Protein Sci. 1993 Mar;2(3):411-9. doi: 10.1002/pro.5560020313.
The IR absorption frequencies as derived from second derivatives of the Fourier transform IR spectra of the amide I' bands of globular proteins in D2O are compared to those obtained from band fitting of the vibrational circular dichroism (VCD) spectra. The two sets of frequencies are in very good agreement, yielding consistent ranges where amide I' VCD and IR features occur. Use of VCD to complement the IR allows one to add sign information to the frequency information so that features occurring in the overlapping frequency ranges that might arise from different secondary structures can be better discriminated. From this comparison, it is clear that correlation just of the frequency of a given IR transition to secondary structure can lead to a nonunique solution. Different sign patterns were identified for correlated groups of globular proteins in restricted frequency ranges that have been previously assigned to defined secondary structural elements. Hence, different secondary structural elements must contribute band components to a given frequency range.
将重水中球状蛋白质酰胺I'带的傅里叶变换红外光谱二阶导数得出的红外吸收频率，与通过振动圆二色性（VCD）光谱带拟合得到的频率进行比较。这两组频率非常吻合，得出了酰胺I' VCD和红外特征出现的一致范围。使用VCD来补充红外光谱，能让人们在频率信息中加入符号信息，从而更好地区分重叠频率范围内可能由不同二级结构产生的特征。通过这种比较可以清楚地看出，仅将给定红外跃迁的频率与二级结构相关联可能会导致非唯一解。在先前已指定为特定二级结构元件的受限频率范围内，为相关球状蛋白质组确定了不同的符号模式。因此，不同的二级结构元件必定会为给定频率范围贡献谱带成分。
