The inactivation of the biological properties of insulin by 131 I labelling or irradation.

The various biological properties of crystalline insulin labelled with131I and crystalline insulin submitted to irradiation were studied. The properties investigated were the hypoglycemie, convulsive and antigenic activities, and the effect on the glucose uptake of the diaphragm and the epididymal fat pad of the rat. It was observed that the131I-insulin rapidly lost its hypoglycemie activity and its insulin effectin vitro, whereas the antigenic and the convulsive activities were retained longer. The irradiated insulin behaved in the same manner. The influence of the radioactive labelling was also studied on the reaction between insulin and anti-insulin antibodies.