Multiple forms of ADP‐glucose pyrophosphorylase from tomato leaf

ADP‐glucose pyrophosphorylase (AGP, EC 2.7.7.27) was partially purified from tomato ( Lycopersicon esculentum Mill. cv. Laura) leaf by a procedure previously used for purification of AGP from tomato pericarp. SDS‐PAGE and western blot analysis of the final preparation indicated that the leaf enzyme is composed of two subunits of 50 and 54 kDa. Two‐dimensional PAGE and western blot analysis of the same preparation, however, revealed at least six isoforms of the large subunit and two isoforms of the small subunit. The leaf AGP is very sensitive to regulation by 3‐phosphoglycerate and inorganic phosphate. Its properties are compared to those of AGP from tomato fruit.