Carter C W, Kraut J
Proc Natl Acad Sci U S A. 1974 Feb;71(2):283-7. doi: 10.1073/pnas.71.2.283.
Pairs of antiparallel beta polypeptide-chain segments in known protein structures are usually observed to form right-handed double helixes with helix parameters in the same range as those of nucleic acids. We have constructed a model containing only standard bond lengths, bond angles, and dihedral angles in which such a polypeptide double helix fits precisely into the minor groove of an RNA double helix with identical helix parameters. The geometry of the RNA portion is essentially a hybrid between those of the A and A' forms. Hydrogen bonds can be made between the ribose 2'-hydroxyls and polypeptide carbonyl oxygens. Since such precise complementarity between the stable conformations of RNA and polypeptides is unlikely to be merely coincidental, we propose that it played a fundamental role in the initiation of precellular evolution. Specificially, we propose that the two double-helical structures are mutually catalytic for assembly of one another from activated precursors in the prebiotic soup, and moreover that they provide some degree of genetic coding.
在已知的蛋白质结构中，反平行β多肽链段对通常会形成右手双螺旋，其螺旋参数与核酸的螺旋参数处于相同范围。我们构建了一个仅包含标准键长、键角和二面角的模型，在该模型中，这样的多肽双螺旋能够精确地契合到具有相同螺旋参数的RNA双螺旋的小沟中。RNA部分的几何结构本质上是A和A'形式的混合体。核糖2'-羟基与多肽羰基氧之间可以形成氢键。由于RNA和多肽的稳定构象之间如此精确的互补性不太可能仅仅是巧合，我们提出它在细胞前进化的起始过程中发挥了重要作用。具体而言，我们提出这两种双螺旋结构在从益生元汤中的活化前体相互组装时相互催化，而且它们还提供了一定程度的遗传编码。
