Characterization of super-active insulin,prolactin and placental lactogen

Complexes between insulin, prolactin or placental lactogen and cyanogen bromide-activated Sepharose release hormone-like materials when treated with bovine serum albumin (BSA) (1). These materials have enhanced biological activities, and are, presumably, N₁N₂-disubstituted guanidines in which the hormones and BSA are the substituents. The present studies show that ammonium bicarbonate can substitute for BSA in the generation of the super-active hormones. Super-activity of the released, guanidinated hormones, therefore, can be manifested in the absence of the BSA substituent. The key derivatized amino acid residues have not yet been identified, but it appears that guanidination of lysine is either unnecessary or insufficient. Several operational considerations which are important for the demonstration of these enhanced activities are discussed.