Quantitative Studies on the Precipitation of Anti-2,4-Dinitrophenyl Antibody in Antigen Excess

Abstract

Decrease in precipitation of purified rabbit anti-2,4-dinitrophenyl (DNP) antibody in antigen excess was studied with various DNP-proteins under different conditions of pH and salt concentration. It was shown that the tendency to form soluble complexes in antigen excess depends upon the nature of the protein to which DNP is coupled. DNP-proteins which have a greater charge density and thus a greater tendency to enter aqueous solution, as indicated by their solubility under different conditions of pH and salt concentration, their behavior on acid-base titration, and their electrophoretic mobility, have a greater tendency to form soluble complexes in antigen excess, and their precipitation with antibody is more readily inhibited by the presence of free hapten.