Mechanism of aminoacylation of tRNA. Influence of spermine on the kinetics of aminoacyl-tRNA synthetases by isoleucyl- and valyl-tRNA synthetases from Mycobacterium smegmatis.
Isoleucyl-tRNA synthetase has been purified to homogeneity from Mycobacterium smegmatis. The influence of spermine on the kinetics of valyl-tRNA and isoleucyl-tRNA formation has been investigated by Cleland's method (Cleland, W.W. (1963) Biochim. Biophys. Acta 67, 104-137, 173-187, 188-196). The results suggest that in the presence of spermine and suboptimal concentration of Mg2+, the formation of valyl-tRNA and isoleucyl-tRNA follows a sequential mechanism. In the presence of an optimal concentration of Mg2+, both valyl-tRNA and isoleucyl-tRNA formation proceeds by a ping-pong mechanism. However, in the presence of spermine and optimal concentrations of Mg2+, valyl-tRNA formation follows the ping-pong mechanism while isoleucyl-tRNA formation follows the sequential mechanism.
D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D007533:Isoleucine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D009161:Mycobacterium / Q000201:enzymology*; D012346:RNA, Transfer, Amino Acyl / Q000096:biosynthesis*; D013096:Spermine / Q000494:pharmacology*; D014637:Valine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism*
D012346:RNA, Transfer, Amino Acyl; D013096:Spermine; D000604:Amino Acyl-tRNA Synthetases; D007533:Isoleucine-tRNA Ligase; D014637:Valine-tRNA Ligase