Preparation of radioactive iodocasein.

We have recently prepared iodocasein containing radioactive iodine (1’31) for use in studies, to be described in detail elsewhere, on the metabolism of calorigenic substances in human beings. The procedure followed was, in general, that of Reineke and Turner (1,2) except for modifications necessitated by the incorporation and handling of Pal. These modifications shorten the procedure somewhat and aid in obtaining conveniently a product having sufficient specific activity and biologic potency. It is the purpose of the present paper to describe the preparation and properties of the radioactive iodocasein so obtained.’