Facile chemoenzymatic synthesis of a novel stable mimic of NAD(+)

Nicotinamide adenine dinucleotide (NAD(+)) is an essential cofactor participating in a variety of important enzyme-catalyzed physiological and pathophysiological processes. Analogues of NAD(+) provide key and valuable agents for investigating NAD(+)-dependent enzymes. In this study, we report the preparation of a novel stable NAD(+) mimic, 4′-thioribose NAD(+) (S-NAD(+)), using a facile and efficient chemoenzymatic approach. Substrate activity assays indicated the resulting S-NAD(+) is chemically inert to human CD38 and sirtuin 2 enzymes, but capable of participating in redox reactions in a manner similar to NAD(+). X-ray crystallographic analysis revealed binding of S-NAD(+) to the active site of human CD38 and critical residues involved in leaving group activation and catalysis. By more closely mimicking NAD(+) in geometry and electrostatics, the generated S-NAD(+) offers a unique and important tool that can be extended to study enzymes utilizing NAD(+).