Nadn

NADn is a nonstandard term that appears in some scientific literature and databases to denote NAD-related species or an NAD analogue used in research. There is no universally accepted definition; the meaning of NADn varies by author or dataset, and in many cases it functions as a placeholder for a noncanonical form of nicotinamide adenine dinucleotide introduced for experimental purposes.

In practice, NADn has been used to refer to modified dinucleotides in which the nicotinamide ring, adenine moiety, or phosphate linkages are altered to affect redox properties, binding affinity, or to enable detection. Such NADn analogs are used as substrate mimics, inhibitors, or probes in NAD-dependent enzyme studies, including dehydrogenases and sirtuins. They can be designed to resist enzymatic turnover, act as mechanism-based inhibitors, or carry detectable tags for assay readouts.

Synthesis and detection typically involve chemical synthesis of the modified dinucleotide, followed by purification and characterization. Analytical methods such as high-performance liquid chromatography, mass spectrometry, and sometimes fluorescence or radiolabeling are used to verify identity and monitor interactions.

Limitations: The lack of standardization means experimental results with NADn analogs may not extrapolate across systems; enzyme compatibility and assay conditions heavily influence outcomes. Researchers should clearly define the specific NADn variant used in their work.

See also: Nicotinamide adenine dinucleotide (NAD+), NADH, NADP+, NADPH, nicotinamide riboside.