Biologically active thiocarbamyl derivatives of insulin

Abstract Insulin was reacted with phenyl isothiocyanate and with allyl isothiocyanate. When this reaction was carried out in aqueous buffer solutions, biologically active phenylthiocarbamyl and allylthiocarbamyl insulin derivatives were obtained. Solubility properties, biological activity, and the amount of free amino groups were determined for a number of these insulin derivatives. A color reaction was applied to the identification of thiohydantoins. This reaction was also used in the paper chromatography of allyl- and phenylthiocarbamyl insulin hydrolylzates. The terminal amino acids involved in the reaction with the isothiocyanates were identified by their thiohydantoins in the chromatograms of the ether extracts of the hydrolyzates of the insulin derivatives. Complete agreement with Sanger's findings is reported.