Atomic force microscopy of A-gliadin fibrils and in situ degradation

Atomic force microscopy (AFM) has been used in air and in aqueous buffer to study the structure of fibrils formed by the self-assembly of A-gliadin protein molecules. The images showed fibrils with a diameter of between 15 and 30 nm and lengths ranging from about 100 nm to 2 μm. No branched fibrils were observed, and there was no indication of a strong lateral inter-fibril interaction that would result in side-by-side association. Disassembly of the fibrils occurred when the pH of the aqueous buffer was reduced. In contrast the reverse process of fibril assembly and adsorption to the mica surface was less readily observed in situ. Some short fibrils were observed to assemble, but the lengths and densities were considerably less than those obtained by external deposition and drying. (C) 2000 Academic Press.