Peptide C-terminal α-amidating enzyme purified to homogeneity from Xenopus laevis skin

Kensaku Mizuno, Junichiro Sakata, Masayasu Kojima, Kenji Kangawa, Hisayuki Matsuo

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67 Citations (Scopus)


The C-terminal α-amide formation of the peptides is one of the most important events of prohormone processing. In this study, we have developed a simple and sensitive assay for monitoring α-amidating activity by using radioiodinated Ac-Tyr-Phe-Gly as a substrate. By utilizing this assay, an α-amidating enzyme was first purified to homogeneity from Xenopus laevis skin. The purified enzyme has a single polypeptide chain with an apparent molecular weight of 39,000 and its N-terminal sequence was determined as Ser-Leu-Ser-. The enzyme converts several synthetic peptides with C-terminal glycine to the corresponding des-glycine peptide α-amides. The enzyme activity, with an optimal pH 6-7, was dependent on the copper ion and ascorbate. In the presence of 0.25 mM ascorbate, the enzyme exhibited a Km of 0.35 μM and a Vmax of 1.9 nmol/μg/h for Ac-Tyr-Phe-Gly.

Original languageEnglish
Pages (from-to)984-991
Number of pages8
JournalBiochemical and biophysical research communications
Issue number3
Publication statusPublished - 1986 Jun 30
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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