Observations on the composition and activity of partially arylated insulin

Abstract

The application of 2,4,5-trinitrotoluene to the prepn. of labelled derivatives of insulin was examined. The glycine amino terminals of insulin were found to react more quickly than phenylalanine and these more rapidly than lysine. The reaction with all the free amino groups and with the tyrosine phenolic groups was found to be markedly dependent on the pH of the medium. By stopping the reaction after an appropriate time, insulin derivatives were made which are soluble in water and which retain some or all of the activity of the original protein. The distr. of masked amino groups in such dinitrotolyl deriva- tives suggests that the free amino groups are not essential to the hormonal action of insulin.