Chothia C
Cambridge Centre for Protein Engineering, UK.
Ciba Found Symp. 1991;162:36-49; discussion 49-57. doi: 10.1002/9780470514160.ch4.
The asymmetry of L-amino acids determines the asymmetrical features of alpha-helices and beta-sheets. These in turn determine two principal aspects of the three-dimensional structure of proteins: the preferred ways in which alpha-helices and beta-sheets pack together, and certain topological features of the paths followed by polypeptide chains through structures. Though the asymmetrical nature of amino acids plays the central role in determining the asymmetrical aspects of protein structures, it has little or no influence on the next level of biological structures--assemblies of protein molecules.
L-氨基酸的不对称性决定了α螺旋和β折叠的不对称特征。这些特征进而决定了蛋白质三维结构的两个主要方面：α螺旋和β折叠聚集在一起的优选方式，以及多肽链在结构中所遵循路径的某些拓扑特征。尽管氨基酸的不对称性质在决定蛋白质结构的不对称方面起着核心作用，但它对下一级生物结构——蛋白质分子的组装几乎没有影响。
