Purification and characterization of the mitochondrial F₁ atpase from Sorghum

Abstract

Purification and kinetic analysis of the sorghum mitochondrial F₁ ATPase was attempted in order to understand the behaviour of plant monocot F₁ ATPases. The purified F₁ ATPase consisted of 6 subunits viz. α , β , γ , δ ', δ and ε unlike other monocot F₁ ATPases reported so far. The additional subunit designated as δ ' is larger in size than the δ subunit, unlike in other dicot ATPase preparations. The enzyme has a low specific activity and is markedly affected by anions like bicarbonate and sulphite and cations like Mg²⁺ and Mn²⁺. It shows no Ca²⁺ dependent ATPase activity and has a very low GTPase activity, compared with other plant ATPases. Comparison of the sorghum ATPase with ATPases from other members of Gramineae reveals differences in their characteristics within the same family.