NADH is an important coenzyme produced in vivo during dehydrogenase
based enzymatic reactions and it has a number of
essential roles in biological systems. It acts as a coenzyme in
redox reactions, as a donor of Adenosine diphosphate (ADP)-ribose
moieties in ADP-ribosylation reactions, as a precursor of the second
messenger molecule cyclic ADP-ribose, as well as acting as a
substrate for bacterial DNA ligases and a group of enzymes called
sirtuins that use NAD+ to remove acetyl groups from proteins. In
addition to these metabolic functions, NAD+ emerges as an adenine
nucleotide that can be released from cells spontaneously and
by regulated mechanisms and can so have important extracellular
roles. The electrochemical oxidation of NADH has attracted
considerable attention due to its importance both as a cofactor fo