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Kinetics of the purified plasma membrane H + ‐ATPase from red beet ( Beta vulgaris )
Author(s) -
Vara Luis E. González,
BaizabalAguirre Víctor M.,
Medina Guadalupe
Publication year - 1992
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1992.tb01336.x
Subject(s) - lysophosphatidylcholine , atpase , biochemistry , chemistry , membrane , kinetics , vanadate , enzyme , adenosine triphosphate , centrifugation , chromatography , phosphatidylcholine , phospholipid , physics , quantum mechanics
The plasma membrane H + ‐ATPase (EC 3.6.1.35) was purified by washing red beet ( Beta vulgaris L.) plasma membranes with sodium deoxycholate and separating the ATPase, solubilized with lysophosphatidylcholine, by centrifugation in a glycerol gradient. The purified H + ‐ATPase had a sedimentation coefficient of about 8S. In the absence of exogenous protein substrates, the purified ATPase preparation did not present protein kinase activity. Compared with the H + ‐ATPase in the plasma membrane, the purified ATPase presented a higher affinity for adenosine 5′‐triphosphate (ATP) and a lower sensitivity to the inhibitors vanadate and inorganic phosphate. These changes in the kinetics of the ATPase could also be observed by treating the membranes with lysophosphatidylcholine, without purifying the enzyme. These results can be explained assuming that lysophosphatidylcholine interacts with the ATPase altering its kinetics probably by stimulating the transformation from the inhibitor‐binding conformation E2 into the ATP‐binding conformation E1.