The use of some ATP analogues for the analysis of the mechanism of ATP hydrolysis by the organic pyrophosphatase of wheat seedlings.

The present experiments have shown that the activity of organic pyrophosphatase from microsomes of wheat seedlings is strongly inhibited by alpha, beta-methylene and gamma-thio-ATP derivatives, which inhibit the hydrolysis of both ATP and ADP. It has been found that the main products of ATP hydrolysis are not ADP but AMP and orthophosphate. The rate of hydrolysis of ATP is not increased by addition of ADP to the incubation medium. The ratio of the reaction products, Pi and AMP, amounts to 1.7-1.8 with ATP as substrate and is close to 1.0 with ADP.