Open AccessCharacterization of the Solubilized Plasma Membrane ATPase of Red Beet
Author(s) -
Donald P. Briskin,
Ronald J. Poole
Publication year - 1984
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.76.1.26
Subject(s) - chemistry , atpase , membrane , enzyme , kinetics , chromatography , substrate (aquarium) , extraction (chemistry) , biochemistry , phosphorylation , biophysics , biology , physics , quantum mechanics , ecology
The plasma membrane ATP-phosphohydrolase (ATPase) from red beet (Beta vulgaris L.) storage tissue was solubilized with the zwitterionic detergent Zwittergent 3-14 from a plasma membrane-enriched fraction which was extracted with the anionic detergent, sodium deoxycholate. For both the extraction of extraneous proteins by deoxycholate and the solubilization of active plasma membrane ATPase by Zwittergent 3-14, the optimal concentration of detergent was 0.1% (weight per volume) with a detergent to protein ratio of 1.0 (milligram per milligram). The properties of the solubilized ATPase were found to be similar to the membrane-bound enzyme with respect to pH optimum, substrate specificity, inhibitor sensitivity, and kinetics of K(+) stimulation. The solubilized ATPase preparation formed a rapidly turning over phosphoenzyme, the breakdown velocity of which was increased in the presence of 50 millimolar KCl. Solubilization with 0.1% Zwittergent 3-14 following extraction with 0.1% deoxycholate resulted in an increase in both ATPase activity and steady state phosphoenzyme level; however, a direct correspondence between the increase in ATPase activity and phosphorylation level did not exist. It is proposed that this discrepancy may be the result of a detergent-mediated modification of kinetic rate constants in the mechanism of the enzyme.