[Characteristics of the structure and specificity of aspartyl- and valyl-tRNA-synthetases from muscle tissue of long-fasting rabbits].

Amino acid compositions of aspartyl- and valyl-tRNA synthetases from the muscles of long-fasting and normal rabbits were studied. Certain differences in amino acid content of fasted and normal rabbits were found. The possibility of incorrect aminoacylation was shown for the tRNA and amino-acyl-tRNA synthetases (ARS) from the muscles of experimental animals.

[Effect of cadmium ions on the rate of the tRNA aminoacylation reaction].

Cadmium ions are studied for their effect on the reaction rate of tRNA aminoacylation which was carried out using overall preparations of aminoacyl-tRNA-synthetases (ARSases) isolated from muscles of male rabbits and from three-day pea seedling roots. Cadmium in the concentration of 3 X 10(-5) M is established to accelerate the reaction rate two times as compared to the norm. Other bivalent cations of metals lack this ability.

[Isolation and purification of aspartyl- and valyl-tRNA-synthetases from muscles of normal and long-fasting rabbits. Structural characteristics and various kinetic parameters].

Highly purified aspartyl- and valyl-tRNA synthetases were obtained by 6-stage purification from normal and long-fasting rabbit's muscles. The molecular masses of the enzymes are (120 +/- 10) X 10(3). These proteins consist of two subunits (alpha 2-type) with (60 +/- 10) X X 10(3) molecular mass as determined by electrophoresis in SDS polyacrylamide gel.

[Spectral characteristics of muscle aspartyl- and valyl-tRNA- synthetases in normal animals and in an experimental model of prolonged starvation].

Conformational differences between asparagyl- and valyl-tRNA synthetases from normal (ARSn) and long-fasting (ARSf) rabbit's muscle were revealed by means of UV fluorescence and differential spectroscopy. The fluorescence spectra indicate more hydrophobic environment of tryptophan residues in the ARSf's at similar quantum yields. The differential absorption spectra reveal the distinctions between tryptophanyl microenvironments for ARS's of different amino acid specificity and for ARSn's and ARSf's of the same specificity.