Abstract: The invention provides an isolated formate dehydrogenase (FDH) polypeptide specific for NADP+ and an isolated FDH polypeptide having an adenine ribose recognition loop comprising a first large amino acid and a second amino acid, wherein the first and second amino acid are arranged in space to allow the second amino acid to bond with a phosphate group. Also provided is a variant of an BAD+ specific FDH polypeptide, wherein the adenine ribose recognition loop has been mutated at least one position to alter the three dimensional polypeptide structure of the adenine ribose recognition loop to allow a phosphate group to be recognised. The polypeptides of the invention can be used in the conversion of NADP+ to NADP or in the conversion of BAD+ to NASH.

Abstract: Novel FDH enzymes are provided herein, including novel NADPH-specific and NADH-specific FDH enzymes. Additionally, methods are provided utilizing these novel enzymes in catalytic systems for in situ regeneration of NADPH or NADH. Further aspects of the invention relate to the definition and use of crystal structures of these novel enzymes.