Biomedical subjects

G A Nevinskiĭ

Publications and source records attributed to G A Nevinskiĭ.

2 recordsLinked to original sources

PubMedDate not supplied

[Specific modification of phenylalanine:tRNA-ligases of E. coli MRE-600 with N-chlorambucilyl-14c-phenylalanyl-tRNA].

N-Chlorambucilyl-[14C]phenylalanyl-tRNA was used for the affinity modification of phenylalanine : tRNA-ligase from E. coli MRE-600. It has been found that N-chlorambucilyl-[14C]phenylalanyl-tRNA selectively inactivates phenylalanine : tRNA-lagase that results in formation of a covalent bond between the tRNA derivative and the enzyme at pH 5.8, 25 degrees C. The rate fall of the aminoacylation of tRNA with [14C]phenylalanine was observed after the enzyme incubation with N-chlorambucilyl-[14C]phenylalanyl-tRNA at pH 7.5, 25 degrees C. It has been shown that this modification results in a similar rate decrease of tRNA aminoacylation with [14C]phenylalanine, ATP-[32P]pyrophosphate exchange and reaction of the enzymatic deacylation of [14C]phenylalanyl-tRNA. This fact evidences in favour of the possibility of the alkylation to proceed in the proximity of the active centre of the enzyme. The covalent complex obtained seems to be an interesting model for the studies of the mechanisms involved in tRNA aminoacylation as well as for elucidation of the tertiary structure of tRNA bound with the enzyme.

Adenosine Triphosphate↗

PubMedDate not supplied

[Influence of the structure of photoreactive ATP analogs on the affinity modification of phenylalanyl-tRNA synsthetase. Modification of the enzyme at two types of nucleotide sites].

ATP gamma-(p-azidoanilidate) (1) and ATP gamma-(p-azidobenzyl)-methylanilidate (2) were shown to be competitive inhibitors for ATP and amino acid in tRNA aminoacylation catalyzed by E. coli MRE-600 phenylalanyl-tRNA synthetase (E.C.6.1.1.20). Low concentration (10(-5)--10(-6) M) of either ATP, gamma-anilidate or GMP stimulates the aminoacylation of tRNA suggesting their interaction with some nucleotide binding sites of the enzyme other than catalytic ones. Covalent photobinding of (1) to the enzyme does not inhibit aminoacylation, nor does it prevent nucleotides from activating the enzyme. UV-irradiation of the synthetase in the presence of (2) results in complete inactivation of the enzyme which can be prevented by phenylalanine or phenylalanine-ATP to save 50% of the enzyme activity but not ATP and tRNA. The photobinding of (2) to the enzyme in the presence of phenylalanine and ATP removes the activation of the enzyme by nucleotides suggesting that both the catalytic and effector sites of the synthetase are blocked in the same manner by compound (2).

Adenosine Triphosphate↗