Non-deleterious dinitrophenyl (DNP) hapten labelling of antibody protein. Preparation and properties of some short-chain DNP imidoesters.

Methyl 3-(2,4- dinitrophenylamino ) propionimidate hydrochloride (DNP-N-IE), methyl 3-(2,4-dinitrophenyl-N-methylamino) propionimidate hydrochloride (DNP- NMe -IE), and methyl 3-(2,4- dinitrophenylthio ) propionimidate hydrochloride (DNP-S-IE) have been prepared. DNP-N-IE and DNP- NMe -IE both react efficiently at 0-2 degrees C and pH 7-9.5 with sheep immunoglobulin G. At least 12 DNP groups can be introduced into the antibody protein without causing any significant change in its antigen binding affinity or capacity.