Effect of aluminum ions on the activities of tRNALeu and leucyl-tRNA synthetase in mouse liver in vivo and in vitro

2 Institute for Biomedical Research, Kaunas University of Medicine, Eivenių 4, LT-50009 Kaunas, Lithuania The object of the study was to evaluate the effect of aluminum ions (Al3+) on activity of tRNALeu and leucyl-tRNA synthetase from mouse liver in vivo and in vitro. Experiments were done on white laboratory mice using intraperitoneal injections of 0.5 LD50 AlCl3 solution (25 mg Al 3+/kg body mass). The acceptor activity of tRNALeu was evaluated by the formation of [14C]-leucyltRNALeu. The leucyl-tRNA synthetase activity was measured by the initial rate of tRNALeu aminoacylation. We determined the effect of Al3+ on the activities of translation machinery components in mouse liver in vivo and in vitro. 16 h after treatment with Al3+ the acceptor activity of tRNALeu decreased by 23%. However, Al3+ caused an increase of leucyl-tRNA synthetase activity in the total preparation of aminoacyl-tRNA synthetases by 20%. We supposed that the increase in leucyl-tRNA synthetase activity is part of compensatory response to the diminished activity of tRNALeu in vivo. Aluminum ions inhibit the acceptor activity of tRNALeu in vitro by 15–20% in the presence of different concentrations of Al3+ (5–40 μM). On the other hand, even low concentrations of Al3+ (5–10 μM) inhibit the activity of leucyl-tRNA synthetase by 19–25%. In the presence of 40 μM of Al3+ activity of this enzyme was only 40% as compared to control. These data show that Al3+ has a significant influence on the components of translation machinery in mouse liver in vivo and in vitro.