Abstract 1467 Evidence of a catalytic dyad in F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium tuberculosis

F420-dependent glucose-6-phosphate dehydrogenase (FGD) catalyzes the conversion of glucose-6-phosphate (G6P) to 6-phosphogluconolactone, using cofactor F420 as the hydride transfer acceptor. The proposed mechanism of FGD suggests that E109 serves as an active site an active site acid, donating a proton to the N-1 position of F420, and H40 would then act as a base abstracting a proton from G6P, facilitating the hydride transfer to the cofactor. Our previous pH-dependence studies supports the hypothesis that E109 is an active site acid, while leaving the role of H40 largely unanswered.