Heliyon. 2019 Sep 10;5(9):e02436. doi: 10.1016/j.heliyon.2019.e02436. eCollection 2019 Sep.
Heliyon
John Donlon, Patrick Ryan
PMID: 31528749 PMCID: PMC6739457 DOI: 10.1016/j.heliyon.2019.e02436
C-terminal α-amidation of peptides is an important event in the course of pro-hormone and neuropeptide processing; it is a modification that contributes to the biological activity and stability of about 25 peptides in neural and endocrine systems. This laboratory has shown that bovine growth hormone (bGH) also has a catalytic function, i.e. peptidylglycine monooxygenase activity, which is the first step in the alpha-amidation of glycine-extended peptides. We report here that the peptidylglycine monooxygenase activity of monomeric bovine pituitary GH, in the presence of ascorbate, is stimulated by combination with oligomeric forms of bGH one of which is a hetero-oligomer with metallothionein. Three species of recombinant monomeric GH (bovine, human and chicken) also catalyze this monooxygenase reaction. Tetrahydrobiopterin also functions as a reductant - with a significantly greater turnover than achieved with ascorbate. These findings clarify the role of GH in peptidylglycine monooxygenation and provide an explanation for earlier observations that peptide amidation is not totally obliterated in the absence of ascorbate, in cultured pituitary cells or
Keywords: Bifunctional protein; Biochemistry; Growth hormone; Oligomers; Peptide amidation; Peptidyglycine monooxygenase; Tetrahydrobiopterin
