Susi H, Byler D M
Eastern Regional Research Center, United States Department of Agriculture, Philadelphia, Pennsylvania 19118.
Arch Biochem Biophys. 1987 Nov 1;258(2):465-9. doi: 10.1016/0003-9861(87)90367-5.
Deconvolved and second derivative Fourier transform infrared spectra of the proteins flavodoxin and triosephosphate isomerase have been obtained in the 1600 to 1700 cm-1 (amide I) region. To our knowledge these results provide the first experimental infrared data on proteins with parallel beta-chains. Characteristic absorption bands for the parallel beta-segments are observed at 1626-1639 cm-1 (strong) and close to 1675 cm-1 (weak). Previous theoretical studies based on hypothetical models with large, regular beta-sheets had suggested bands close to 1650 and 1666 cm-1. Our new assignments were confirmed by band area measurements, which yield conformational information in good agreement with results from X-ray diffraction data. The spectra were compared with corresponding spectra of concanavalin A and carboxypeptidase A. The first contains only antiparallel beta-segments, the second "mixed" beta-segments, with some strands lying antiparallel and others parallel. None of the observed amide I band frequencies assigned to parallel beta-chains occurs in the 1650 cm-1 region associated with helical segments.
已获得黄素氧还蛋白和磷酸丙糖异构酶在1600至1700厘米-1（酰胺I）区域的去卷积和二阶导数傅里叶变换红外光谱。据我们所知，这些结果提供了关于具有平行β链蛋白质的首批实验红外数据。在1626 - 1639厘米-1（强）和接近1675厘米-1（弱）处观察到平行β段的特征吸收带。先前基于具有大的规则β折叠片的假设模型的理论研究曾提出接近1650和1666厘米-1的谱带。通过谱带面积测量证实了我们的新归属，其产生的构象信息与X射线衍射数据的结果高度一致。将这些光谱与伴刀豆球蛋白A和羧肽酶A的相应光谱进行了比较。前者仅包含反平行β段，后者包含“混合”β段，其中一些链反平行排列，另一些平行排列。分配给平行β链的观察到的酰胺I谱带频率均未出现在与螺旋段相关的1650厘米-1区域。
