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ADPGlucose Pyrophosphorylase (ADPG PPase) catalyzes the rate-limiting step of glucan biosynthesis in plants and bacteria. The successful engineering of ADPG PPase will allow for the production of more renewable and biodegradable carbon. Thermodesulfovibrio yellowstonii (Td.y) ADPG PPase shows only ~30% identity to other bacterial forms of the enzyme; at positions E15, F18, F23, S25, and S28 the Td.y enzyme differs from consensus in the glycine rich (positions 9-17) and KRAKPAV regions (positions 23-29), areas known to play roles in activity and allosteric regulation. These positions were targeted for mutagenesis and the enzymes purified using hydroxyapitite and DEAE chromatography. For wild-type (WT), kinetic studies revealed a Vmax of 5.3 U/mg and S0.5 values of 4.0 mM, 13.9 mM, and 1.2 mM for ATP, Mg, and G1P, respectively. Metabolites PEP, G6P, and 3PGA increased the Vmax by 1.5-3 fold and decreased the S0.5 values for ATP by 4.2, 10.3, and 3.8 fold, respectively. Initial kinetics for the variant S25A ...