ACTH(1-8) and ACTH(9-13)NH2 were used as potential enzyme inhibitors to begin examining the relationship between the acetylation of ACTH- and β-endorphin-related peptides. ACTH(1-8) was a potent inhibitor of the acetylation of both ACTH- and β-endorphin-related peptides, whereas ACTH(9-13)NH2 was an effective inhibitor only of the acetylation of ACTH-related substrates. This inhibition pattern indicated that there may be an unusual interaction between some ACTH- and β-endorphin-related peptides as substrates for the acetyltransferase. Utilizing HPLC to separate ACTH- and β-endorphin-related peptides present in the same reaction mixture, ACTH(1-14) and β-endorphin(1-27) at Km and saturating concentrations were used as substrates to examine the ability of one peptide substrate to affect the acetylation of the other. It was observed that the acetylation of ACTH(1-14), even at Km concentration, was relatively unaffected by the presence of β-endorphin(1-27). However, the acetylation of β-endorphin(1-27) was significantly reduced by the presence of ACTH(1-14). This preferential acetylation of ACTH-related peptides over the acetylation of β-endorphin-related peptides might have physiological importance under some conditions.
- Neurointermediate pituitary
- Reversed-phase high pressure liquid chromatography
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience