Glycosidic linkage rotations determine amylose stretching mechanism.

The primary mechanism for relieving tensile strain in alpha-linked polysaccharides (e.g., [alpha-d-Glc-(1-->4)alpha-d-Glc]n) is achieved by complex rotations of the glycosidic linkages. This is shown through computer simulations of atomic force microscopy stretching experiments in combination with free energy calculations of the unfolding pattern for amylose. The experimental force-extension curve is reproduced and analyzed to reveal that the chair-to-boat conversions play a smaller role than previously proposed.