ELECTRON-SPIN-RESONANCE STUDIES OF WHEAT-PROTEIN FRACTIONS

Gluten was fractionated according to its extractability in dilute acid, generating fractions that differed in their gliadin/glutenin ratio and polymer composition. The fractions were characterized by SE-HPLC and by densitometry of electrophoregrams. The hydrated fractions were studied by electron spin resonance spectroscopy. Spin-probing was carried out with nitroxide radicals of various sizes, giving knowledge on the mobility and distribution of molecules in the system. The existence of at least two different aqueous environments was established within the system. Specific spin-labeling of the sulfhydryl or amine groups of protein enabled comparative studies of the rigidity of the protein chains. A factor of variation was found to be the quantity and size of prolamine, but this was not the only criterion.