Arnott S, Bond P J
Science. 1973 Jul 6;181(4094):68-9. doi: 10.1126/science.181.4094.68.
The structure of the complex involving one polyadenylic acid and two polyinosinic acid chains has been determined by x-ray diffraction. The three coaxial, helical chains have conformations like conventional RNA double helices despite the absence of purine-pyrimidine pairing. Formation of hypoxanthine pairs in codon-anticodon interactions therefore requires only trivial changes in the conformation of a standard nucleotide. Evolution of the contemporary genetic code involving purine-pyrimidine complementarity from a primeval code with only adenine-hypoxanthine pairing would have been possible without major discontinuities in molecular geometry.
通过X射线衍射确定了包含一条聚腺苷酸链和两条聚肌苷酸链的复合物的结构。尽管不存在嘌呤-嘧啶配对，但这三条同轴螺旋链具有与传统RNA双螺旋类似的构象。因此，在密码子-反密码子相互作用中次黄嘌呤对的形成仅需要标准核苷酸构象的微小变化。从仅具有腺嘌呤-次黄嘌呤配对的原始密码子进化到具有嘌呤-嘧啶互补性的现代遗传密码，在分子几何结构上可能没有重大间断。
