IMMUNOLOGICAL CROSS-REACTIVITY BETWEEN PROTON-PUMPING INORGANIC PYROPHOSPHATASES OF WIDELY PHYLOGENIC SEPARATED SPECIES

Immunological cross-reactivity among three types of inorganic pyrophosphatases, that is, the proton pumping inorganic pyrophosphate synthase (H+-PPi synthase) and the soluble inorganic pyrophosphatase, both from Rhodospirillum rubrum, and the vacuolar membrane inorganic pyrophosphatase (H+-PPase) from mung bean (Vigna radiata), were examined by means of immunoblot analyses. Antibodies raised against the mung bean H+-PPase cross-reacted with the H+-PPi synthase from R. rubrum but not with the soluble PPase from R. rubrum. N,N′-dicyclohexylcarbodiimide (DCCD), which inhibits both synthesis and hydrolysis of PPi catalysed by purified and chromatophore H+-PPi synthase, binds to the enzyme as shown by fluorography of [14C]DCCD labelling. These results suggest that the R. rubrum H+-PPase share close structural similarities with the vacuolar H+-PPase from Mung bean. © 1991.