Amylose (
CAS_ 9005-82-7) is a planar
polymer of
glucose linked mainly by a(1?4) bonds. It can be made of several thousand glucose units. It is one of the two components of
starch, the other being
amylopectin.
The a(1?4) bonds promote the formation of a helix structure. The structural formula of amylose is pictured at right. The number of repeated glucose subunits (n) can be many thousands (usually in the range of 300 to 3000).
Amylose starch is less readily digested than amylopectin; however, it takes up less space so is preferred for storage in plants it makes-up about 30% of the stored starch in plants. The digestive enzyme amylase works on the ends of the starch molecule, breaking it down into sugars.
High-amylose varieties of rice have a much lower glycemic load, which could be beneficial for diabetics.
