Studies on the cold-insoluble fraction of the water-extractable soybean proteins. II. Factors influencing conformation changes in the 11 S component

Abstract Ultracentrifugal studies indicate that the 11 S globulin of soybeans is capable of undergoing conformation changes probably involving dissociation into subunits which appear to be one-half and approximately one-eighth the size of the 11 S molecule. These changes occur at low ionic strength at alkaline pH values, at moderate ionic strengths at acid pH values, in the presence of sodium octylbenzene sulfonate and in the presence of relatively low concentrations of urea. The conformation changes generated at low ionic strength and alkaline pH are reversible on increasing the ionic strength. Those generated by low concentrations of detergent are also reversible on removal of the detergent and an increase in the ionic strength at neutral pH. Conformation forms of the protein generated at acid pH, or at higher concentrations of detergent, while similar in sedimenting properties to those (above) exhibiting reversibility, are irreversible.