Catalytic Asymmetry in Homodimeric H+-Pumping Membrane Pyrophosphatase Demonstrated by Non-Hydrolyzable Pyrophosphate Analogs.

ABSTRACT: Membrane-bound inorganic pyrophosphatase (mPPase) resembles the F-ATPase in catalyzing polyphosphate-energized H+ and Na+ transport across lipid membranes, but differs structurally and mechanistically. Homodimeric mPPase likely uses a "direct coupling" mechanism, in which the proton generated from the water nucleophile at the entrance to the ion conductance channel is transported across the membrane or triggers Na+ transport. The structural aspects of this mechanism, including subunit cooperation, are still poorly understood. Using a refined enzyme assay, we examined the inhibition of K+-dependent H+-transporting mPPase from Desulfitobacterium hafniensee by three non-hydrolyzable PPi analogs (imidodiphosphate and C-substituted bisphosphonates). The kinetic data demonstrated negative cooper

SUBMITTER: Anashkin VA 

PROVIDER: S-EPMC8469034 | biostudies-literature | 2021 Sep

REPOSITORIES: biostudies-literature