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Evidence for a membrane‐bound pyrophosphatase in Dictyostelium discoideum
Author(s) -
MacDonald James I.S.,
Weeks Gerald
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80214-x
Subject(s) - dictyostelium discoideum , pyrophosphatase , vanadate , pyrophosphatases , inorganic pyrophosphatase , pyrophosphate , biochemistry , enzyme , atpase , membrane , enzyme assay , chemistry , biology , gene
Plasma membrane enriched fractions of Dictyostelium discoideum contain a Des‐insensitive ATPase activity that can be fractionated by DEAE‐Sephacel into a major vanadate‐sensitive activity and a minor vanadate‐insensitive activity. The vanadate‐insensitive activity hydrolysed pyrophosphate considerably more rapidly than ATP or any other substrate tested, and the enzyme was therefore designated a pyrophosphatase. The enzyme had no activity on AMP or p ‐nitrophenyl phosphate. The pyrophosphatase activity was maximal at alkaline pH values and stimulated by Mg 2+ but not by Ca 2+ , properties of the enzyme that are very similar to those of the previously characterized pyrophosphatases of the plant tonoplast membrane. The pyrophosphatase activity of total membrane extracts changed very little during Dictyostelium differentiation.