Definition: Amylopectin is a polysaccharide and highly branched polymer of glucose found in plants. It is one of the two components of starch, the other being amylose. It is not soluble in water.
Glucose units are linked in a linear way with α(1→4) glycosidic bonds. Branching takes place with α(1→6) bonds occurring every 24 to 30 glucose units. In contrast, amylose contains very few α(1→6) bonds which causes it to be hydrolyzed more slowly but have higher density.
Its counterpart in animals is glycogen which has the same composition and structure, but with more extensive branching that occurs every 8 to 12 glucose units.
Plants store starch within specialized organelles called amyloplasts. When energy is needed for cell work, the plant hydrolyzes the starch releasing the glucose subunits. Humans and other animals that eat plant foods also use amylase, an enzyme that assists in breaking down amylopectin.
Starch is made of about 70% amylopectin by weight, though it varies depending on the source (higher in medium-grain rice till 100% in waxy rice, waxy potato starch and waxy corn and lower in long-grain rice, amylomaize and russet potato, for example). Amylopectin is highly branched, being formed of 2,000 to 200,000 glucose units. Its inner chains are formed of 20-24 glucose subunits.
See alo
