Galloway J W
Cancer Research Campaign, London, UK.
Ciba Found Symp. 1991;162:16-29; discussion 29-35. doi: 10.1002/9780470514160.ch3.
The helix is the most common and the most readily recognized example of an enantiomorphic structure. Helical proteins and DNA are good examples of structures where a clear explanation can be provided as to why they adopt one hand or the other. Proteins and DNA are composed of chiral building blocks, amino acids and nucleotides, respectively. Only the L-amino acids occur in proteins; this uniformity of handedness is a prerequisite for helix formation and thus, one could argue, for the development of higher life forms. Helical proteins form higher order helical structures, from collagen and viral capsids to cotton fibres.
螺旋结构是对映体结构中最常见且最容易识别的例子。螺旋状蛋白质和DNA就是很好的结构示例，对于它们为何呈现某一种手性可以给出清晰的解释。蛋白质和DNA分别由手性构件，即氨基酸和核苷酸组成。蛋白质中只存在L - 氨基酸；这种手性的一致性是形成螺旋结构的先决条件，因此可以说，也是高等生命形式发展的先决条件。螺旋状蛋白质形成更高阶的螺旋结构，从胶原蛋白、病毒衣壳到棉纤维。
