[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.

[Spectral characteristics of muscle aspartyl- and valyl-tRNA- synthetases and their complexes with substrates in normal conditions and after prolonged starvation].

Spectral characteristics of aminoacyl-tRNA-synthetases (ARSases) isolated from muscles of normal rabbits and of those fasted for a long time were studied by the methods of fluorescence and differential spectroscopy. Fluorescence spectra and differential absorption spectra of the compared proteins evidenced for more hydrophobic surrounding of tryptophanyls and their less accessibility for Cs+ ions in proteins of fasted animals. Interaction of aspartyl- and valyl-tRNA-synthetases from muscles of normal and long-fasted rabbits with substrates is accompanied by the essential quenching of tryptophan fluorescence of ARSases.

[Amino-tRNA-synthetase activity of rabbit muscles in fasting and aging].

The aminoacyl-tRNA-synthetase activity of muscular soluble fraction was studied in normal rabbits, in those fasting for a long period and old rabbits. A rigion of linear dependence is found for the initial rate of the tRNA aminoacylation reaction on the concentration of the enzymic preparation and also on the substrate amount. Having valuated the initial rate of the aminoacylation reaction, the asparagil- and valyl-tRNA-synthetase activities of muscles were determined in normal rabbits, in those fasting for a long period and in old rabbits.

[Effect of fasting on aminoacylation of tRNA from rabbit muscles].

The aminoacylation of tRNA from muscles was studied in the fasting rabbits. It is shown that under equal conditions of incubation the intensity of the process is higher in the fasting animals. It may be a result of an increase in the content or activity of leucil-tRNA-synthetase in muscles of the fasting rabbits, that is testified by the evidence on the level of aminoacylation in heterologous systems.

[Conformational changes in rabbit muscle aldolase under normal conditions and following prolonged starvation].

The experiments were aimed at studying conformation differences of muscle aldolase in normal rabbits and those fasting for a long time and at finding the areas of polypeptide chains affected by the changes. For this purpose the difference, temperature- and solvent-perturbation spectra of the compared proteins were examined. On the basis of the data obtained on the same amount of chromophore groups in both proteins a conclusion is drawn on a more hydrophobic surrounding of tyrosine and tryptophan residues in aldolase of the long-fasting animals.

[Changes in the primary structure of rabbit muscle aldolase under the influence of valine against a background of prolonged fasting].

The primary structure of the muscle aldolase molecule was studied as affected by semilethal doses of valine administered the abdominal cavity of the rabbits after a long fasting. It is established that in spite of differences in the amino acid composition of the protein, uniformity of the peptides distribution in the process of bromo-cyanogen fragments elution and the total amount of amino acid residues in the identical fragments are maintained. Changes are found only in the point-replacements by amino acids in C-fragment of the molecule (asparagine is replaced by valine and threonine by serine).