[Structural-functional analysis of the complex between phosphorylase B and adenosine-5'-chloromethylphosphonate]. / Strukturno-funktsional'nyi analiz kompleksa fosforilazy B s adenozin-5'-khlormentilfosfonatom.

A complex of phosphorylase B with a tritium-containing AMP analogue, adenosine-5'-chloromethylphosphonate, was obtained. It is found on the basis of the results of the determination of N- and C-terminal amino acids, amino acid composition and sequence, that the peptide 1, modified by adenosine-5'-chloromethylphosphonate, corresponds to the fragment 185-191 in the primary structure of phosphorylase B, and is probably located in the allosteric center of the enzyme. The peptide 2, which is bound with the AMP analogue and corresponds to the fragment 795-798, is suggested to be located at the site of binding the second AMP molecule. The arginine residue 184 is discussed as a possible functional amino acid protein interacting with 5'-phosphate AMP group.

[Inhibition of leucyl-tRNA-synthetases by modified ATP analogs]. / Ingibirovanie leitsil-tRNK-sintetaz modifitsiruiushchimi analogami ATP.

The interaction between modifying ATP analogs containing alkylating or phosphorylating groups in the polyphosphate moiety of the ATP molecule and leucyl-tRNA synthetases from cytoplasm and chloroplasts of Euglena gracilis (strain Z) was studied. It was shown that most of the ATP analogs irreversibly inhibit the cytoplasmic enzyme, having no inhibiting effect on the chloroplast synthetase. The kinetic constants K1 and k2 for the interaction between the most effective irreversible inhibitors and the cytoplasmic enzyme were determined. The data on the protection of the enzyme activity by substrates against irreversible inhibition suggest, that the effect of the adenosine 5'-(beta-chloroethyl phosphate) is directed to the ATP-binding site of the cytoplasmic enzyme, whereas the mixed anhydride of AMP and mesithylene carbonic acid acts predominantly on the binding site of 3'-terminal adenosine of the tRNALeu molecule. ATP analogs may be effectively used for affinity labelling of the cytoplasmic leucyl-tRNA synthetase.