Conversion of the N-terminal serine residue of corticotrophin into glycine

Abstract

Corticotrophin A1 has been treated with periodate to yield a derivative which has been isolated by ion-exchange chromatography. It has a lower retention volume than the corticotrophin in the chroma-tographic system and is presumed to have a glyoxylyl group in place of the N-terminal serine residue. Transamination to convert this group into a glycine residue was attempted by treating the derivative with copper glutamate, and a further product was obtained which possesses the retention volume of the original corticotrophin. The final product has been characterized and it appears to differ from the original corticotrophin only in possessing a N-terminal glycine residue in place of serine. Preliminary observations that the product has the same corticotrophic activity as the native hormone are quoted.