Corticotropins (ACTH). IX. Investigations on the serine and tyrosine residues in α-corticotropin

Abstract

The recovery of N-terminal serine has been investigated with the dinitrophenylated N-terminal octapeptide of α-corticotropin and with a modified corticotropin from which the first two amino acids (serine and tyrosine) have been removed. The yield of DNP-serine in all cases was from 10 to 20% of the theoretically expected value. These results are similar to those previously reported for intact corticotropin. The p K′ of the tyrosine phenolic groups of α-corticotropin has been found by spectrophotometric methods to be 10.01 ± 0.08.