Amylose
From Proteopedia
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| - | '''Amylose''' is a linear polymer of glucose that occurs in starch. It occurs in foods such as grains and potatoes, and it is a major source of energy (calories) in most diets. There are three major forms of amylose, A, B, and V, that differ in the three-dimensional structure. Amylose can also occur with an undefined structure, for example when cooked in water. Amylose is distinct from amylopectin, which is a branched polymer of glucose, and from [[cellulose]], which is a linear polymer of glucose that differs in stereochemistry from amylose. | + | '''Amylose''' is a linear polymer of glucose that occurs in starch. It occurs in foods such as grains and potatoes, and it is a major source of energy (calories) in most diets. There are three major forms of crystalline amylose, A, B, and V, that differ in the three-dimensional structure. Amylose can also occur with an undefined structure, for example when cooked in water. Amylose is distinct from amylopectin, which is a branched polymer of glucose, and from [[cellulose]], which is a linear polymer of glucose that differs in stereochemistry from amylose. In the context of naturally occurring starch, parts of amylopectin form semi-crystalline layers, while amylose occurs in the amorphous parts. |
==Structure== | ==Structure== | ||
<StructureSection load='' size='340' side='right' caption='Caption for this structure' scene='82/824003/Amylose_v/4'> | <StructureSection load='' size='340' side='right' caption='Caption for this structure' scene='82/824003/Amylose_v/4'> | ||
| - | <scene name='82/824003/Amylose_a/3'>Amylose A</scene> and B occur as parallel double-helices of glucose chains, with 6 glucose units per turn. In contrast, <scene name='82/824003/Amylose_v/2'>amylose V</scene> occurs as a single helix as shown in the figure (same structure shown as <scene name='82/824003/Amylose_v/3'>cartoon</scene>). A more irregular conformation of a cyclic amylose occurs is found in complex with a protein in the structure [[5jiw]]. | + | <scene name='82/824003/Amylose_a/3'>Amylose A</scene> and B occur as parallel double-helices of glucose chains, with 6 glucose units per turn. In contrast, <scene name='82/824003/Amylose_v/2'>amylose V</scene> occurs as a single helix as shown in the figure (same structure shown as <scene name='82/824003/Amylose_v/3'>cartoon</scene>). A more irregular conformation of a cyclic amylose occurs is found in complex with a protein in the structure [[5jiw]]. In solution, amylose occurs as flexible hydrated single helices. These can bind to small molecules to form inclusion complexes such as the famous starch/iodine/iodide complex. Because of the difficulty in characterizing non-crystalline or semi-crystalline polymeric materials with complex chemical makeup (variation in chain length and location of branch points), the structure of starch and its components <ref>DOI:10.1002/star.201000013</ref> is less well characterized than that of proteins. |
</StructureSection> | </StructureSection> | ||
Revision as of 14:53, 29 May 2025
Amylose is a linear polymer of glucose that occurs in starch. It occurs in foods such as grains and potatoes, and it is a major source of energy (calories) in most diets. There are three major forms of crystalline amylose, A, B, and V, that differ in the three-dimensional structure. Amylose can also occur with an undefined structure, for example when cooked in water. Amylose is distinct from amylopectin, which is a branched polymer of glucose, and from cellulose, which is a linear polymer of glucose that differs in stereochemistry from amylose. In the context of naturally occurring starch, parts of amylopectin form semi-crystalline layers, while amylose occurs in the amorphous parts.
Structure
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