title: Chemical modification study of aminoacyl-tRNA conformation.
abstract: Chemical reactivity of cytosines in 32P-labeled E. coli tRNA1Leu, E. coli tRNAPhe and yeast tRNAPhe before and after aminoacylation was examined by use of a cytosine-specific reagent, semicarbazide-bisulfite mixture. In all the three tRNA species examined, the cytosine residues that were susceptible to the modification were the same in the aminoacylated tRNA and the unacylated tRNA. Only a limited number of the cytosine residues were modifiable: those that occur in the anticodon, the 3'-CCA terminus, the D-loop, and the extra loop. The sites accessible by the reagent are in good agreement with the general three-dimensional structure of tRNA proposed in literature. These results indicate that the gross conformation of these tRNAs does not change on aminoacylation, and consequently favor the view that the T psi C(G) sequence could become exposed in later steps of protein synthesis in order to achieve the binding of aminoacyl tRNA to ribosomes.
mesh_terms: D000926:Anticodon; D001483:Base Sequence; D003596:Cytosine; D004926:Escherichia coli; D007930:Leucine; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000032:analysis; D010649:Phenylalanine; D012346:RNA, Transfer, Amino Acyl; D012441:Saccharomyces cerevisiae; D012663:Semicarbazides; D013447:Sulfites
chemical_list: D000926:Anticodon; D009843:Oligoribonucleotides; D012346:RNA, Transfer, Amino Acyl; D012663:Semicarbazides; D013447:Sulfites; D010649:Phenylalanine; D003596:Cytosine; D007930:Leucine