Holloway P W, Buchheit C
Department of Biochemistry, University of Virginia School of Medicine, Charlottesville 22908.
Biochemistry. 1990 Oct 16;29(41):9631-7. doi: 10.1021/bi00493a018.
Fourier-transform infrared spectroscopy was used to examine the secondary structure of the membrane-binding domain (nonpolar peptide) of rabbit liver cytochrome b5 in D2O and in the presence of phospholipids and deoxycholate. In all situations, the predominant structure was alpha helix, but an examination of the components of the amide I band in the spectrum of the nonpolar peptide showed that the major peak was shifted from 1655 cm-1 in the lipids to 1650 cm-1 in deoxycholate. This shift to lower frequency, together with a decrease in intensity of the amide II band, is indicative of N-H to N-D exchange of the peptide backbone. A semiquantitative analysis indicated that the alpha helix of the peptide is over 95% exchanged in the presence of deoxycholate but is only 10% exchanged in the presence of lipid. These data suggest that the membrane-inserted portion of the peptide is alpha helical and is largely protected from N-H to N-D exchange by the bilayer. We suggest that this technique appears to provide a general method for determining the type of secondary structure involved in membrane interaction and the percentage of this structure which is involved in the interaction.
利用傅里叶变换红外光谱法，在重水（D₂O）中以及存在磷脂和脱氧胆酸盐的情况下，研究兔肝细胞色素b5膜结合结构域（非极性肽）的二级结构。在所有情况下，主要结构均为α螺旋，但对非极性肽光谱中酰胺I带的成分进行检测发现，主峰从脂质中的1655厘米⁻¹移至脱氧胆酸盐中的1650厘米⁻¹。这种向低频的移动，连同酰胺II带强度的降低，表明肽主链发生了N-H到N-D的交换。半定量分析表明，在脱氧胆酸盐存在下，肽的α螺旋超过95%发生了交换，而在脂质存在下仅10%发生了交换。这些数据表明，肽的膜插入部分呈α螺旋结构，并且在很大程度上受到双层膜的保护，免受N-H到N-D的交换。我们认为，该技术似乎提供了一种通用方法，用于确定参与膜相互作用的二级结构类型以及参与这种相互作用的该结构的百分比。
