Assuntos
Nucleotídeos de Adenina/análise , Plantas/análise , RNA/análise , Sequência de Bases , Células Cultivadas , Centrifugação com Gradiente de Concentração , Cromatografia por Troca Iônica , Meios de Cultura , Nucleotídeos de Citosina/metabolismo , Eletroforese em Gel de Poliacrilamida , Nucleotídeos de Guanina/metabolismo , Cinética , Oryza , Fosfatos/metabolismo , Isótopos de Fósforo , Células Vegetais , Polirribossomos/análise , RNA/biossíntese , RNA Ribossômico/análise , Ribonucleotídeos/análise , Espectrofotometria Ultravioleta , Fatores de Tempo , UltrafiltraçãoRESUMO
Embryos from rice (Oryza sativa L. var. Bluebonnet) and wheat (Triticum aestivum L.) contain an aminoacyl-tRNA protein transferase which transfers arginine from arginyl-tRNA to the N terminus of a protein acceptor. The activity was measured in vitro in a reaction mixture containing embryo supernatant fraction, buffer, sulfhydryl reagent, and arginyl-tRNA. It was not dependent on the usual cofactors for ribosomal protein synthesis, nor was it sensitive to cycloheximide or puromycin. However, the activity was inhibited by ribonuclease. The enzyme was purified 33-fold from a crude homogenate of rice embryos. An apparent endogenous substrate from rice embryos was prepared free of transferase activity; however, the transferase was not purified sufficiently to show absolute dependence on the presence of this endogenous substrate.
