Soy Protein Isolate Components and Their Interactions

SILVANA PETRUCCELLI; AÑÓN, M. C.

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

American Chemical Society

Lugar: Davis; Año: 1995 vol. 43 p. 1762 - 1767

0021-8561

The electrophoretic behavior of a soy protein isolate was analyzed in both nonreducing and reducing SDS-PAGE. Aggregates formed by ? and ?? subunits of ?-conglycinin exhibited both ionic interactions and disulfide bonds. Higher molecular weight aggregates (180 000-190 000) consisted of trimers or dimers of ?? and ? subunits, whereas those of intermediate molecular weight (115 000-120 000) were formed by ??,? subunits of ?-conglycinin and A polypeptides of glycinin. The latter exhibited a higher sensitivity toward changes of ionic strength and thermal treatments. The proportion of ?? and ? subunits of the isolate which was included in these aggregates is highly dependant on the freeze-drying conditions. These aggregates were readily reduced in the presence of Na2SO3, even at low concentrations and in the absence of denaturing agents, thus suggesting that the disulfide bonds involved were accessible. These aggregates were stable at different pH values, in the presence of both SDS and urea.