title: Multistep mechanism of codon recognition by transfer ribonucleic acid.
abstract: The mechanism of codon recognition by tRNA is investigated in the system tRNAPhe + UUC by temperature-jump measurements using the Wye base fluorescence as a label. In 0.4 M Na+ and 5 mM Mg2+ a two-step reaction is observed and described quantitatively; UUC is shown to bind preferentially to one of two conformations on the anticodon loop. In 0.1 m Na+ and 10 mM Mg2+ an additional relaxation effect is observed, which indicates a codon-induced conformation change leading to an association of tRNA molecules. The codon-induced tRNA association is demonstrated independently by equilibrium sedimentation. The present results suggest a more active role of tRNA during translation than anticipated.
mesh_terms: D003062:Codon; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009690:Nucleic Acid Conformation; D010649:Phenylalanine; D012333:RNA, Messenger; D012343:RNA, Transfer / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics
chemical_list: D003062:Codon; D012333:RNA, Messenger; D010649:Phenylalanine; D012343:RNA, Transfer; D012964:Sodium; D008274:Magnesium