Shimizu M
Nucleic Acids Symp Ser. 1982(11):139-42.
In the previous symposium, it was pointed out that a complex of the anticodon bases and the discriminator base on the tRNA could recognize the corresponding protein amino acid by a key and lock relation. There are two possibilities to make this complex: (1) a set of two L shaped tRNAs in a head and tail conformation (2) the possibility for an U shaped structure of the tRNA. By using the HGS molecular model, the whole tRNAs were constructed and the above possibilities were checked. In both cases, the C4Ns were easily formed as expected. In the 2L case, the alpha helixes on the aminoacyl tRNA synthetase were found to fit the grooves on the two tRNAs beautifully. The C4N was formed just on the Rossmann fold of the synthetase. In the U case, since the uracyl at the 8th position at the D stem could have a covalent bonding to synthetase, the C4N is again formed over the Rossmann fold. After the amino acid charging, the tRNA could have an extended, T C exposed, structure. In concerning with this conformational change, the amino acid uptake through membrane by the specific uncharged tRNA can be a good evidence for the direct interaction between the amino acids and its cognate tRNAs, thus for the C4N.
在之前的研讨会上指出，tRNA上的反密码子碱基和鉴别碱基复合体能够通过锁钥关系识别相应的蛋白质氨基酸。形成这种复合体有两种可能性：（1）一组两个呈头尾构象的L形tRNA；（2）tRNA呈U形结构的可能性。通过使用HGS分子模型构建了完整的tRNA并检验了上述可能性。在这两种情况下，如预期的那样，C4N很容易形成。在两个L形tRNA的情况中，发现氨酰tRNA合成酶上的α螺旋与两个tRNA上的凹槽完美契合。C4N正好在合成酶的罗斯曼折叠处形成。在U形tRNA的情况中，由于D茎第8位的尿嘧啶可能与合成酶形成共价键，C4N同样在罗斯曼折叠处形成。氨基酸负载后，tRNA可能具有延伸的、暴露TC的结构。关于这种构象变化，特定的无负载tRNA通过膜摄取氨基酸可以很好地证明氨基酸与其同源tRNA之间的直接相互作用，从而证明C4N的存在。
