Holloway P W, Mantsch H H
Division of Chemistry, National Research Council of Canada, Ottawa, Ontario.
Biochemistry. 1989 Feb 7;28(3):931-5. doi: 10.1021/bi00429a002.
Fourier-transform infrared spectroscopy was used to examine the secondary structure of rabbit liver cytochrome b5 and the polar and nonpolar domains of the protein. The data for both the polar and nonpolar domains agree well with those previously obtained by other physical techniques. In particular it was found that the nonpolar membrane-binding domain was predominantly alpha helix and that the polar domain was also highly helical, but not all alpha helix. The independence of the two domains in the whole molecule was, in general, confirmed by the additivity of the spectra of the two domains. The small differences that were seen indicate that there is a loss of alpha helix when the protein is cut into the two domains. In addition, there appeared to be a slight difference in the exposure to solvent of the amide NH groups in the alpha-helical portion of the nonpolar domain when it was examined in isolation.
利用傅里叶变换红外光谱法研究了兔肝细胞色素b5的二级结构以及该蛋白质的极性和非极性结构域。极性和非极性结构域的数据与先前通过其他物理技术获得的数据吻合良好。特别值得注意的是，发现非极性膜结合结构域主要为α螺旋，极性结构域也高度螺旋化，但并非全是α螺旋。一般来说，两个结构域在整个分子中的独立性通过两个结构域光谱的加和性得到了证实。观察到的微小差异表明，当蛋白质被切割成两个结构域时，α螺旋会有所损失。此外，当单独检测非极性结构域的α螺旋部分时，发现酰胺NH基团暴露于溶剂中的情况似乎略有不同。
