Improved preparation and assay and some characteristics of Cl--ATPase activity from Limonium vulgare

We present a revised method for the preparation, storage and assay of the Cl--ATPase activity responsible for salt secretion in Limonium vulgare. Altering the centrifugation step improved the yield and linked-enzyme assay for ADP provided a sensitive method for continuous monitoring of Cl--ATPase activity. The activity of untreated membranes was low but fairly stable. Treatment with detergent gave strong stimulation of Cl--ATPase activity ATP between 0.1 and 0.2 mM. Cl- stimulated the activity up to a maximum at 0.13 M Cl-, and the pH optimum was around 6.3 to 6.4.