NADHdependent

NADHdependent is a term used to describe enzymes or reactions that require NADH as a cofactor to donate electrons. NADH stands for the reduced form of nicotinamide adenine dinucleotide, a central electron carrier in cellular metabolism. In many cells, NADH is produced by catabolic pathways such as glycolysis and the citric acid cycle and is consumed by pathways that regenerate NAD+, as well as in various redox-balancing steps.

NADH-dependent enzymes are typically oxidoreductases that transfer electrons from NADH to an organic substrate, reducing the substrate while NADH is oxidized to NAD+. The direction of the reaction depends on substrate availability and the cellular NAD+/NADH ratio. In anaerobic metabolism, lactate dehydrogenase uses NADH to reduce pyruvate to lactate, regenerating NAD+ to sustain glycolysis. Alcohol dehydrogenase uses NADH to reduce acetaldehyde to ethanol. Glycerol-3-phosphate dehydrogenase in the cytosol uses NADH to reduce dihydroxyacetone phosphate to glycerol-3-phosphate, linking carbohydrate metabolism to lipid biosynthesis.

In research and biotechnology, NADH-dependent enzymes are studied for their kinetic properties, cofactor specificity, and suitability for engineered redox-balanced pathways. They are often contrasted with NADPH-dependent reductases, which preferentially supply electrons for biosynthetic processes in different cellular compartments. NADHdependency highlights the role of NADH in energy metabolism and redox homeostasis across diverse biological systems. See also NADH, NADPH, and oxidoreductase.