Enolase is the enzyme involved in the metabolism of carbohydrates — specifically, a workhorse of glycolysis, the pathway that breaks glucose down for energy. It catalyses the conversion of 2-phosphoglycerate to phosphoenolpyruvate, one of the late steps before pyruvate, and it needs magnesium ions to function. The enzyme is ancient and universal, found in organisms from bacteria to humans, which tells its evolutionary importance: every cell that burns sugar runs glycolysis, and every glycolysis needs enolase. In food science it appears in fermentation biochemistry — yeast glycolysis drives brewing and baking — and in dental research, where fluoride’s inhibition of bacterial enolase is part of how it suppresses the acid production behind caries. A single enzyme, quietly central to the energy economy of life.