PURIFICATION AND CHARACTERIZATION OF THE MITOCHONDRIAL F1 ATPASE FROMRICE

The mitochondrial F-1 ATPase from rice has been purified to homogeneit y. One of the characteristic features of this ATPase is that it consis ts of six subunits of sizes 55 kDa (alpha + beta), 36 kDa (gamma), 26. 2 kDa (delta'), 22 kDa (delta) and Il kDa (epsilon) unlike other monoc ot F-1 ATPases. It exhibits typical non-linear kinetics for ATP and ca n be stimulated by oxyanions like bicarbonate and sulphite. High conce ntrations of sulphite (> 10 mM) markedly inhibit the ATPase. Compared to maize F-1 ATPase, it has a relatively lower GTPase activity and com pletely lacks Ca2+ ATPase activity. However, in spite of the differenc es in the kinetic properties of the F-1 ATPases from rice and maize, n o significant differences in the amino acid sequence of alpha and beta subunits of rice and maize are observed except for three amino acid c hanges.