Figure 8.

Proposed mechanism for AA13 PMO action on amylose. The AA13 PMO binds to the amylose double helix in the active-site surface groove (dark blue), with the active site positioned above the α(1→4) linkage. Accessible glycosidic C-H bonds on the amylose sheet are designated with a blue H. The copper active site is shown in orange. Glucose units are shown as hexagons. The amylose chain undergoing oxidation is shown in green. Filled red circles indicate oxygen atoms. H₂O release resulting from each cleavage event is omitted for clarity. Oxidation of the glycosidic linkage results in the release of an An fragment (n = degree of polymerization) (step 1). The PMO can then oxidize and cleave the next available bond to generate an A6 fragment (step 2) and subsequently move along the same helix to generate additional A6 fragments (step 3). Alternatively, following the first oxidation event, the PMO can bind a new portion of the amylose helix to generate A6n fragments (step 5).