Preparation of a highly active ATPase of the mesophilic cyanobacterium Spirulina maxima

In this work, we report new studies on the ATPase attached to the photosynthetic membranes of the mesophilic cyanobacterium Spirulina maxima. This enzyme does not display persistent latency as had been previously reported for the ATPase of Spirulina platensis. The enzyme is readily activated by the careful application of methods currently used to activate chloroplast CF1. Photosynthetic membranes of Spirulina maxima show a Mg(2+)-dependent ATPase activity of 195±25 μmol Pi (mg chl)(-1) h(-1) after a light plus dithiothreitol (DDT) treatment. Methanol treatment of these membranes elicits Mg(2+)-dependent ATPase activity of 222±18 μmol Pi (mg chl)(-1) h(-1).Here, we also describe the purification of the soluble coupling factor AF1 of Spirulina maxima. This enzyme is unique among mesophilic cyanobacterial F1 preparations in regard to its high specific Ca(2+)-dependent ATPase activity after heat treatment (14.75±1.91 μmol Pi (mg prot)(-1) min(-1)) and its room temperature stability.