Panasik N, Brenchley J E, Farber G K
Department of Biochemistry and Molecular Biology, 108 Althouse Laboratory, Pennsylvania State University, 16802, University Park, PA, USA.
Biochim Biophys Acta. 2000 Nov 30;1543(1):189-201. doi: 10.1016/s0167-4838(00)00182-5.
Analysis of the structural basis for thermostability in proteins has come mainly from pairwise comparisons of mesophilic and thermophilic structures and has often yielded conflicting results. Interpretation of these results would be enhanced by knowing the normal range of features found for mesophilic proteins. In order to provide the average and distribution values of structural features among similar mesophilic proteins, we compared the amino acid composition, solvent accessible surface area, hydrogen bonds, number of ion pairs, and thermal factors of 22 structures of alpha/beta barrel glycosyl hydrolases. These distributions are then compared to values from seven alpha/beta barrel glycosyl hydrolases from thermophilic organisms. We find that the distribution of each structural feature is broad within the mesophilic proteins and illustrates the difficulty of making pairwise comparisons of mesophiles to thermophiles where differences for individual proteins may be within the normal range for the group. In comparing mesophiles to thermophiles as a group, we find that thermophilic structures have fewer glycines in a particular region of the structure and higher thermal factors at room temperature. These results suggest the basis for thermostability may be related to protein motion rather than to static features of protein structure.
对蛋白质热稳定性结构基础的分析主要来自嗜温菌和嗜热菌结构的成对比较，且常常得出相互矛盾的结果。若了解嗜温菌蛋白质的正常特征范围，将有助于对这些结果的解读。为了提供相似嗜温菌蛋白质结构特征的平均值和分布值，我们比较了22种α/β桶状糖基水解酶的氨基酸组成、溶剂可及表面积、氢键、离子对数量和热因子。然后将这些分布与来自嗜热生物的7种α/β桶状糖基水解酶的值进行比较。我们发现，嗜温菌蛋白质中每种结构特征的分布范围都很广，这表明将嗜温菌与嗜热菌进行成对比较存在困难，因为单个蛋白质的差异可能在该组的正常范围内。在将嗜温菌作为一个整体与嗜热菌进行比较时，我们发现嗜热菌结构在结构的特定区域中甘氨酸较少，且在室温下热因子较高。这些结果表明，热稳定性的基础可能与蛋白质运动有关，而非蛋白质结构的静态特征。
