|
|Section2= |Section3= }} Amylose is a helical polymer made of α-D-glucose units, bound to each other through α(1→4) glycosidic bonds. This polysaccharide is one of the two components of starch, making up approximately 20-30% of the structure. The other component is amylopectin, which makes up 70–80% of the structure.〔http://www.gmo-compass.org/eng/glossary/〕 Because of its tightly packed structure, amylose is more resistant to digestion than other starch molecules and is therefore an important form of resistant starch, which has been found to be an effective prebiotic.〔http://www.healthyeatingclub.org/info/articles/nutrients/resisstarch.htm〕 ==Structure== 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).〔Nelson, David , and Michael M. Cox. Principles of Biochemistry. 5th ed. New York: W. H. Freeman and Company , 2008.〕 The structural formula of amylose is pictured at right. The number of repeated glucose subunits (n) is usually in the range of 300 to 3000, but can be many thousands. There are three main forms of amylose chains can take. It can exist in a disordered amorphous conformation or two different helical forms. It can bind with itself in a double helix (A or B form), or it can bind with another hydrophobic guest molecule such as iodine, a fatty acid, or an aromatic compound. This is known as the V form and is how amylopectin binds to amylose to form starch. Within this group, there are many different variations. Each is notated with V and then a subscript indicating the number of glucose units per turn. The most common is the V6 form, which has six glucose units a turn. V8 and possibly V7 forms exist as well. These provide an even larger space for the guest molecule to bind. This linear structure can have some rotation around the phi and psi angles, but for the most part bound glucose ring oxygens lie on one side of the structure. The α(1→4) structure promotes the formation of a helix structure, making it possible for hydrogen bonds to form between the oxygen atoms bound at the 2-carbon of one glucose molecule and the 3-carbon of the next glucose molecule.〔http://www1.lsbu.ac.uk/water/hysta.html〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Amylose」の詳細全文を読む スポンサード リンク
|