Stimulation of valyl- and isoleucyl-tRNA synthetase reactions by polyamines.
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Date
1979-12
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Abstract
The aminoacylation of tRNA catalysed by valyl-tRNA synthetase (EC
6.1.1.9) and isoleucyl-tRNA synthetase (EC 6.1.1.5) from Mycobacterium smegmatis
is dependent on the presence of divalent metal ions. Polyamines alone, in
the absence of metal ions, do not bring about aminoacylation. In the presence of
suboptimal concentrations of Mg2+, polyamines significantly stimulate the reaction.
Of the cations tested, only Mn2+, Co2+ and Ca2+ can partially substitute for Mg2+
in aminoacylation, and spermine stimulates aminoacylation in the presence of these
cations also. At neutral pH, spermine deacylates nonenzymatically aminoacyl
tRNA. AMP and pyrophosphate-dependent enzymatic deacylation of aminoacyltRNA
(reverse reaction) is also stimulated by spermine. The inhibitory effect of
high concentration of KCl on aminoacylation is counteracted, by spermine. The
low level of activity between pH 8·5-9·0 at 1·2 mM Mg2+ is restored to normal
level on the addition of spermine. The inhibitory effect of high pH on aminoacylation
in the presence of low concentration of Mg2+ is also prevntedvby spemine.
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Keywords
Mycobacterium smegmatis, spermine stimulation, isoleucyl-tRNA synthetase, valyl-tRNA synthetase
Citation
Natarajan V, Gopinathan K P. Stimulation of valyl- and isoleucyl-tRNA synthetase reactions by polyamines. Journal of Biosciences. 1979 Dec; 1(4): 357-367.