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 a nd polymer composition. The fractions were characterized by SE-HPLC an d by densitometry of electrophoregrams. The hydrated fractions were st udied by electron spin resonance spectroscopy. Spin-probing was carrie d out with nitroxide radicals of various sizes, giving knowledge on th e 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 o f protein enabled comparative studies of the rigidity of the protein c hains. A factor of variation was found to be the quantity and size of prolamine, but this was not the only criterion.