Temperature and pH dependence of immunoglobulin G conformation.

ABSTRACT

Previous indirect observations have indicated that IgG may change its conformation at low or high pH and at a temperature of about 35 degrees C. By means of small angle neutron scattering a change in the value of the gyration radius of two different native IgG's was observed above 44 degrees C. No similar change was detected when the sample was previously dissolved in an acidic buffer. The acidic pretreatment caused a significant decrease in the gyration radius (Rg) value measured at 20 degrees C which was partially recovered by increasing the temperature. These observations led to the assumption that the main conformational change observed appears either in the hinge region of the molecular or in the interdomain areas separating the constant and the variable domains of the Fab parts.