Beauregard M, Goraj K, Goffin V, Heremans K, Goormaghtigh E, Ruysschaert J M, Martial J A
Laboratorie de Biologie Moléculaire et de Génie Génétique, Université de Liège, Institut de Chimie, Sart Tilman, Belgium.
Protein Eng. 1991 Oct;4(7):745-9. doi: 10.1093/protein/4.7.745.
We present here a spectroscopic structural characterization of octarellin, a recently reported de novo protein modelled on alpha/beta-barrel proteins [K. Goraj, A. Renard and J.A. Martial (1990) Protein Engng, 3, 259-266]. Infrared and Raman spectra analyses of octarellin's secondary structure reveal the expected percentage of alpha-helices (30%) and a higher beta-sheet content (40%) than predicted from the design. When the Raman spectra obtained with octarellin and native triosephosphate isomerase (a natural alpha/beta-barrel) are compared, similar percentages of secondary structures are found. Thermal denaturation of octarellin monitored by CD confirms that its secondary structures are quite stable, whereas its native-like tertiary fold is not. Tyrosine residues, predicted to be partially hidden from solvent, are actually exposed as revealed by Raman and UV absorption spectra. We conclude that the attempted alpha/beta-barrel conformation in octarellin may be loosely packed. The criteria used to design octarellin are discussed and improvements suggested.
我们在此展示了章鱼肽的光谱结构特征，章鱼肽是一种最近报道的基于α/β桶状蛋白构建的全新蛋白质[K. 戈拉伊、A. 勒纳尔和J.A. 马蒂亚尔（1990年）《蛋白质工程》，第3卷，第259 - 266页]。对章鱼肽二级结构的红外和拉曼光谱分析揭示了预期比例的α螺旋（30%）以及比设计预测更高的β折叠含量（40%）。当比较用章鱼肽和天然磷酸丙糖异构酶（一种天然的α/β桶状蛋白）获得的拉曼光谱时，发现二级结构的比例相似。通过圆二色性监测的章鱼肽热变性证实其二级结构相当稳定，而其类似天然的三级折叠结构则不然。拉曼光谱和紫外吸收光谱显示，预测应部分隐藏于溶剂中的酪氨酸残基实际上是暴露的。我们得出结论，章鱼肽中尝试构建的α/β桶状构象可能堆积松散。讨论了用于设计章鱼肽的标准并提出了改进建议。
