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

  • S. T. Prigge
  • R. E. Mains
  • B. A. Eipper
  • L. M. Amzel* **

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.

Copyright information

© Birkhäuser Verlag Basel, 2000

Authors and Affiliations

  • S. T. Prigge
    • 1
  • R. E. Mains
    • 2
  • B. A. Eipper
    • 2
  • L. M. Amzel* **
    • 1
  1. 1.Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore (Maryland 21205, USA)US
  2. 2.Departments of Neuroscience and Physiology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore (Maryland 21205, USA)US