During the breakdown of glucose, NAD+ becomes NADH when the coenzyme...

Core Concept

Dehydrogenase enzymes remove two hydrogen equivalents from substrates such as glyceraldehyde-3-phosphate. One proton plus both electrons transfer onto NAD+, converting it to its reduced form, NADH, while the second proton escapes into solution. NADH then ferries these high-energy electrons to the electron transport chain, where their controlled oxidation powers proton pumping. This paired oxidation and reduction keeps catabolism electrically balanced.