Susanne Selman-Reimer1, Bruce R. Selman1
1Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison-WI 53706, USA
Tóm tắt
The ATPase activity of the chloroplast coupling factor 1 (CF1) isolated from the green alga Dunaliella is completely latent. A brief heat treatment irreversibly induces a Ca2+ ‐dependent activity. The Ca2+ dependent ATPase activity can be reversibly inhibited by ethanol, which changes the divalent cation dependency from Ca2+ to Mg2+. Both the Ca2+ ‐dependent and Mg2+ ‐dependent ATPase activities of heat‐treated Dunaliella CF1 are inhibited by monospecific antisera directed against Chlamydomonas reinhardi CF1. However, when assayed under identical conditions, the Ca2+ ‐dependent ATPase activity is significantly more sensitive to inhibition by the antisera than is the Mg2+ ‐dependent activity. These data are interpreted as indicating that soluble Dunaliella CF1 can exist in a variety of conformations, at least one of which catalyzes a Ca2+ ‐dependent ATPase and two or more of which catalyze an Mg2+ ‐dependent ATPase.
