Graĭfer D M, Zenkova M A, Karpova G G, Malygin A A, Matasova N B
Mol Biol (Mosk). 1990 Jul-Aug;24(4):1076-83.
Binding of labelled oligouridylates--mRNA analogs--to human placenta 80S ribosomes in the presence of Phe-tRNAPhe has been studied. The single site for (pU)n (n = 6, 9, 13) binding on the ribosome was found; association constants for their tRNA-dependent binding were evaluated. In the presence of oligouridylates as templates [14C]Phe-tRNAPhe was found to be able to bind simultaneously at acceptor and donor ribosomal sites which resulted in diphenylalanine formation. The observed maximum Phe-tRNAPhe binding level was considerably lower than for the corresponding oligouridylate binding; the longer oligouridylate the higher Phe-tRNAPhe maximum binding level. To explain the results obtained we have proposed that (i) (Phe)2-tRNA produced from transpeptidation dissociates from the ribosomal A site to a significant extent and (ii) when oligouridylate length increases its interaction with 3'-side of mRNA binding center results in allosteric stabilization of the complex of peptidyl-tRNA with the ribosome at A site.
研究了在苯丙氨酰 - tRNAphe存在下，标记的寡聚尿苷酸（mRNA类似物）与人胎盘80S核糖体的结合情况。发现了核糖体上（pU）n（n = 6、9、13）的单一结合位点；评估了它们依赖tRNA的结合的缔合常数。在以寡聚尿苷酸为模板的情况下，发现[14C]苯丙氨酰 - tRNAphe能够同时在核糖体的受体和供体位点结合，从而导致二苯丙氨酸的形成。观察到的苯丙氨酰 - tRNAphe的最大结合水平明显低于相应寡聚尿苷酸的结合水平；寡聚尿苷酸越长，苯丙氨酰 - tRNAphe的最大结合水平越高。为了解释所获得的结果，我们提出：（i）转肽作用产生的（苯丙氨酸）2 - tRNA在很大程度上从核糖体A位点解离；（ii）当寡聚尿苷酸长度增加时，其与mRNA结合中心3'侧的相互作用导致肽基 - tRNA与核糖体在A位点的复合物的变构稳定。
