Chemical analysis of acetylated bovine growth hormone, a growth-hormone inhibitor.

Purified bovine growth hormone was acetylated with acetic anhydride under various conditions. Acetylated bovine growth hormone prepared in anhydrous acetic anhydride at 43 degrees for 5min. inhibited the growth-promoting response of unmodified bovine growth hormone in hypophysectomized rats. This acetylated bovine growth hormone contained 18 total acetyl groups/mol., which included 12 N(in)-acetyl and 6-8 hydroxylamine-reactive acetyl groups (acetylated aliphatic hydroxy amino acids and 2-3 O-acetyltyrosine residues). Deacetylation of acetylated bovine growth hormone with hydroxylamine at pH9.5 destroyed its ability to inhibit the growth-promoting activity of bovine growth hormone.