Biopolymers and cell. 1986. Volume 2. № 4. 179 - 185
T. I. Merkulova, M. K. Nurbekov,, N. B. Tarusova, G. K. Kovaleva
PHOSPHONATE ANALOGS OF P>, P4-BIS(5'-ADENOSYL)TETRAPHOSPHATE (Ap4A) AS INHIBITORS OF BOVINE TRYPTOPHANYL-tRNA-SYNTHETASE
Summary
Phosphonate analogs of Ap4A—ApcpppA(I), AppcppA(II) and ApcppcpA(III)—inhibit the enzymic activity of bovine tryptophanyl-tRNA-synthetase (EC 6.1.1.2); I effectively interacts with ATP and PPi binding sites, III — mainly with PP* binding site, and II interacts weakly with both of them. After prolonged incubation (5 h, 37 °C) with I or III an irreversible 80 % inhibition of the enzyme is observed, whereas with II it is only 40 %. The inhibiting action of the Ap4A analogs is shown to be due to the removal of essential Zn2+ ion from the enzyme. Based on these observations, an assumption is made that Zn2+ in the active site of the enzyme is located in or near the PP* binding site.