Starch and glycogen (substrates)

Starch and glycogen are large, branched polysaccharides composed of glucose units. Starch is the primary carbohydrate storage molecule in plants, and glycogen serves the same function in animals (sometimes called "animal starch")[3]. Both act as substrates for a suite of metabolic enzymes: glycogen synthase, starch synthase, glycogen phosphorylase, starch phosphorylase, branching enzymes, and debranching enzymes. Their metabolism is critical for maintaining cellular energy levels, responding to hormonal control, and supporting rapid energy mobilization[4][5][7]. Disorders in their metabolism lead to pathological accumulation (e.g., glycogen storage diseases) but the substrates themselves are not the direct targets of drugs—rather, their associated enzymes are[3][5][7]. The true molecular targets in therapeutic contexts are the enzymes/proteins that metabolize starch and glycogen (such as glycogen synthase, glycogen phosphorylase, starch synthase, branching/debranching enzymes), not the substrates. Drugs and clinical biomarkers pertain to those enzymes, not starch/glycogen molecules themselves[3][5].

Other names

animal starchplant starchpolysaccharide carbohydrate substrates