Effect of polyamines on isoleucyl-tRNA formation by rat-liver isoleucyl-tRNA synthetase.
The effect of polyamines on rat-liver isoelucyl-tRNA formation was studied using isoleucyl-tRNA synthetase purified by column chromatography successively on Sephadex G-200, DEAE-Sephadex A-25, and tRNA-Sepharose 4B. In the presence of 50 mMK+, isoleucyl-tRNA formation was inhibited markedly by 1.5 mM or higher concentrations of Mg2+. However, the addition of spermine to the reaction mixture prevented the inhibitory effect of Mg2+. In the presence of 200 mMK+, the addition of spermine to the reaction mixture stimulated isoleucyl-tRNA formation in the presence of Mg2+ concentrations from 0 to 5 mM. Although the effective concentration was different, spermidine exhibited a similar stimulative effect. The effective concentration of spermine required for stimulation was higher when larger amounts of tRNA were used. The stimulatory effect of isoleucyl-tRNA formation by polyamines was shown to reflect on polypeptide synthesis. When formaldehyde-treated poly(A,U) was used as messenger RNA, polypeptide synthesis from amino acids was stimulated by polyamines, but that from aminoacyl-tRNAs was not stimulated by polyamines.
D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D000818:Animals; D007533:Isoleucine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D011700:Putrescine / Q000494:pharmacology*; D012346:RNA, Transfer, Amino Acyl / Q000096:biosynthesis*; D051381:Rats; D012270:Ribosomes / Q000378:metabolism; D013095:Spermidine / Q000494:pharmacology*; D013096:Spermine / Q000494:pharmacology*
D012346:RNA, Transfer, Amino Acyl; D013096:Spermine; D000604:Amino Acyl-tRNA Synthetases; D007533:Isoleucine-tRNA Ligase; D008274:Magnesium; D013095:Spermidine; D011700:Putrescine