The buoyant and potentiometric titrations of human immuno‐gamma globulin

Abstract

AbstractThe buoyant density and potentiometric hydrogen ion titration curves of human immuno‐gamma globulin in 3M cesium chloride have been recorded. In addition, the amino acid analysis of the IgG employed has been completed. The hydration of the protein and the variation of the hydration with pH have been calculated from the buoyant density data. The potentiomtric hydrogen ion titration curve has been employed to estimate the intrinsic pK′s of the acidic and histidyl residues of the molecule, and to confirm the hypothesis that it does in fact conform to the oil drop model of protein conformation. Correlations have been drawn between the three sets of data in the following manner. The results of the potentiometric hydrogen ion titration have been checked against the amino acid analysis to determine whether the numbers of groups observed to titrate and the numbers of groups observed in the amino acid analysis do correspond. Second, previous hypotheses as to the direct correlation between potentiometric hydrogen ion titration behaviour and buoyant density titration behaviour have been investigated and substantially confirmed.