Cellular and Molecular Life Sciences CMLS

, Volume 57, Issue 8, pp 1236–1259

New insights into copper monooxygenases and peptide amidation: structure, mechanism and function

Authors

  • S. T. Prigge
    • Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore (Maryland 21205, USA)
  • R. E. Mains
    • Departments of Neuroscience and Physiology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore (Maryland 21205, USA)
  • B. A. Eipper
    • Departments of Neuroscience and Physiology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore (Maryland 21205, USA)
  • L. M. Amzel* **
    • Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore (Maryland 21205, USA)

DOI: 10.1007/PL00000763

Cite this article as:
Prigge, S., Mains, R., Eipper, B. et al. CMLS, Cell. Mol. Life Sci. (2000) 57: 1236. doi:10.1007/PL00000763

Abstract.

Many bioactive peptides must be amidated at their carboxy terminus to exhibit full activity. Surprisingly, the amides are not generated by a transamidation reaction. Instead, the hormones are synthesized from glycine-extended intermediates that are transformed into active amidated hormones by oxidative cleavage of the glycine N-Cα bond. In higher organisms, this reaction is catalyzed by a single bifunctional enzyme, peptidylglycine α-amidating monooxygenase (PAM). The PAM gene encodes one polypeptide with two enzymes that catalyze the two sequential reactions required for amidation. Peptidylglycine α-hydroxylating monooxygenase (PHM; EC 1.14.17.3) catalyzes the stereospecific hydroxylation of the glycine α-carbon of all the peptidylglycine substrates. The second enzyme, peptidyl-α-hydroxyglycine α-amidating lyase (PAL; EC 4.3.2.5), generates α-amidated peptide product and glyoxylate. PHM contains two redox-active copper atoms that, after reduction by ascorbate, catalyze the reduction of molecular oxygen for the hydroxylation of glycine-extended substrates. The structure of the catalytic core of rat PHM at atomic resolution provides a framework for understanding the broad substrate specificity of PHM, identifying residues critical for PHM activity, and proposing mechanisms for the chemical and electron-transfer steps in catalysis. Since PHM is homologous in sequence and mechanism to dopamine β-monooxygenase (DBM; EC 1.14.17.1), the enzyme that converts dopamine to norepinephrine during catecholamine biosynthesis, these structural and mechanistic insights are extended to DBM.

Key words. Amidation; copper; peptidylglycine α-amidating monooxygenase; dopamine β-monooxygenase; electron transfer; structure; ascorbate; peptide hormones; oxygen chemistry.
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Copyright information

© Birkhäuser Verlag Basel, 2000