[Inactivation of chloroplast CF1-ATPase]

Inactivation of chloroplasts ATPase at alkalization of the medium and under the effect of chaotropic reagent (NaBr) was studied. An increase of the enzyme solution pH was accompanied with an increase of optical density with the wavelength 294 nm due to the dissociation of the enzyme tyrosine residues. The maximum protective effect at inactivation in the alkaline medium is exerted by the complex MgADP. Inactivation with the chaotropic reagent is prevented by the complex MgATP. It is suggested that at a decrease of proton concentration or under the effect of chaotropic hormones two different regions of the enzyme are attacked; one of them specific to ADP, the second-to ATP.