What is the Origin of NAD+ Cycling?

The concept is fundamental to cellular biochemistry and metabolism, with renewed clinical interest driven by longevity research highlighting NAD+'s role as a limiting factor in sirtuin and PARP enzyme activity. The 'cycling' term emphasizes the regenerative nature of this coenzyme and the importance of its continuous regeneration for life-sustaining processes.

What is the Mechanism of NAD+ Cycling?

The mechanism involves two primary pathways: the de novo synthesis from tryptophan and the salvage pathway, which recycles nicotinamide and nicotinamide riboside back into NAD+. Key enzymes like NAMPT (Nicotinamide phosphoribosyltransferase) drive the salvage pathway, ensuring the rapid regeneration of NAD+ from its precursors. Efficient cycling maintains the high NAD+/NADH ratio necessary to power mitochondrial respiration and support DNA repair mechanisms, protecting the genome.

NAD+ Cycling ∞ Area

NAD+ Cycling

Meaning

NAD+ Cycling describes the continuous, essential biochemical process of interconverting Nicotinamide Adenine Dinucleotide (NAD+) and its reduced form, NADH, within the cell to sustain vital metabolic and signaling functions. NAD+ is a critical coenzyme for hundreds of enzymatic reactions, including those involved in energy production (ATP synthesis) and DNA repair, making efficient cycling essential for cellular longevity and metabolic flexibility. Impaired cycling is a hallmark of biological aging and metabolic dysfunction.