Cycloamylose

Cycloamyloses were discovered as a result of studies of the function of 4-α-glucanotransferase, also known as disproportionating enzyme or D-enzyme (EC 2.4.1.25) isolated from potato.

[1] Upon incubation of D-enzyme with high molecular weight amylose, a product was obtained with decreased ability to form a blue complex with iodine, without reducing or non-reducing ends, and resistant to hydrolysis by glucoamylase (an exoamylase).

Takaha and Smith deduced that the product was a cyclic polymer, which they confirmed by mass spectrometry and acid hydrolysis, and showed that it comprised between 17 and several hundred glucose units.

[4][5] In contrast the structure of a larger cycloamylose with 26 glucose units was determined to comprise two short left-handed V-amylose helices in antiparallel arrangement.

[6][7] Cycloamyloses contain cavities in the helices which are capable of accommodating guest molecules, which suggested applications in chemical technologies.