FIGURE 2.

ATP hydrolysis activity of inverted membrane vesicles of M. ruminantium M1. Effect of TBT-Cl and DCCD (A) and amiloride (B) on ATPase activity. Inverted membrane vesicles were preincubated in assay buffer for 30 min at 37 °C in the presence of either TBT-Cl (closed circles) or DCCD (open squares) or amiloride (closed squares) before the reaction was started by the addition of 2.5 mm (final concentration) of sodium-ATP. Controls received solvent only. ATPase activity was determined using a colorimetric assay that measured the amount of inorganic phosphate liberated at 37 °C and pH 6.5. The values are the means of duplicate determinations, and the experimental error associated with these values was less than 15%. One hundred percent activity was equivalent to 28–34 milliunits/mg protein.