The starch polysaccharide amylose has been visualised at the molecular level by atomic force microscopy (AFM). In order to image individual amylose chains, a new method was developed for producing aqueous amylose solutions at room temperature. The method involved incubation of hot amylose solutions with iodine and the non-ionic surfactant Tween-20 (polyoxyethylene sorbitan monolaurate). This process stabilises the amylose molecules such that, after cooling to room temperature, no aggregation takes place. AFM images of the resulting sample revealed a distribution of extended chain-like molecules, and allowed for the first time, direct visualisation of a small number of branched macromolecules. Treatment of the sample with the starch-degrading bacterial α-amylase (EC 184.108.40.206) confirmed the nature of the soluble chain-like polymers.
- Atomic force microscopy