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Amylopectin is highly branched, being formed of 2,000 to 200,000 glucose units. Its inner chains are formed of 20–24 glucose subunits. Structure of the amylopectin molecule. Dissolved amylopectin starch has a lower tendency of retrogradation (a partial recrystallization after cooking—a part of the staling process) during storage and cooling.
Glycogen is an analogue of starch, a glucose polymer that functions as energy storage in plants. It has a structure similar to amylopectin (a component of starch), but is more extensively branched and compact than starch. Both are white powders in their dry state.
It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. [4] Glycogen, the energy reserve of animals, is a more highly branched version of amylopectin.
It is found in grains or granules in the cell's cytoplasm and is composed of an α-linked glucose polymer with a degree of branching intermediate between amylopectin and glycogen, though more similar to the former. The polymers that make up floridean starch are sometimes referred to as "semi-amylopectin". [1]
Glycogen is analogous to starch, a glucose polymer in plants, and is sometimes referred to as animal starch, [16] having a similar structure to amylopectin but more extensively branched and compact than starch. Glycogen is a polymer of α(1→4) glycosidic bonds linked with α(1→6)-linked branches.
Amylose A is a parallel double-helix of linear chains of glucose. Amylose is made up of α(1→4) bound glucose molecules. The carbon atoms on glucose are numbered, starting at the aldehyde (C=O) carbon, so, in amylose, the 1-carbon on one glucose molecule is linked to the 4-carbon on the next glucose molecule (α(1→4) bonds). [3]
In enzymology, a starch synthase (EC 2.4.1.21) is an enzyme that catalyzes the chemical reaction. ADP-glucose + (1,4-alpha-D-glucosyl) n ADP + (1,4-alpha-D-glucosyl) n+1 Thus, the two substrates of this enzyme are ADP-glucose and a chain of D-glucose residues joined by 1,4-alpha-glycosidic bonds, whereas its two products are ADP and an elongated chain of glucose residues.
α-Amylase is an enzyme (EC 3.2.1.1; systematic name 4-α-D-glucan glucanohydrolase) that hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose, through the following biochemical process: [2]