Re‐engineering the discrimination between the oxidized coenzymes NAD+ and NADP+ in clostridial glutamate dehydrogenase and a thorough reappraisal of the coenzyme specificity of the wild‐type enzyme

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Why is it important?

The 3D structure of clostridial GluDH suggested how to change its coenzyme specificity but puzzlingly mutants markedly shifted towards NADPH and away from NADH had shown virtually no improvement with NADP+. Following this up revealed that assumed 1 in 300 activity with NADP+ (compared with NAD+) was actually measuring 1 in 300 contamination of Grade 1 NADP+ by NAD+! Wild-type discrimination between the pure coenzymes is 1 in ~80,000 and the mutants are affected in both directions of reaction.