TRITIUM LABELING OF IMMUNOGLOBULIN WITH IODOACETIC ACID

The labeling of immunoglobulin with iodoacetic acid-2-**3H has been found to be markedly dependent on temperature, pH and time. The optimum labeling conditions combining maximum specific radioactivity with minimum alteration to the antigen binding ability of the labeled immunoglobulin were 70 degree C and pH 9. 8 for 30 min. Bands obtained by the SDS polyacrylamide gel electrophoresis of the labeled preparation were strictly comparable to those of unlabeled immunoglobulin and the protein specific radioactivity was found to be largely confined to polypeptides of molecular weight greater than 1. 6 multiplied by 10**5 daltons. Data are presented in graphical and tabular form.