Reduced pyridine nucleotides induce a conformational change in NQO1 preventing antibodies from binding to the C-terminus.

(A) Immunoblot analysis of rhNQO1 following incubation with trypsin in the absence and presence of NADH. (B, C) Immunoprecipitation of rhNQO1 by antibodies that target the C-terminal domain in the absence and presence of NADH or NADPH. (D) Immunoprecipitation of rhNQO1 by antibodies that target the C-terminal domain in the absence and presence of reduced nicotinamide analogs nicotinamide riboside (NRH) and benzyl dihydronicotinamide (BN). (E) Immunoprecipitation of rhNQO1 by antibodies that target the C-terminal domain following the oxidation of NADH by β-lapachone. (F) Immunoprecipitation of NQO1*1 and NQO1*2 proteins by antibodies that target the C-terminal domain in the absence and presence of NADH. Reaction conditions for immunoprecipitation studies are described in Materials and methods.