Iron and copper complexation by angiotensin-converting enzyme inhibitors. A study by ultraviolet spectroscopy and electrospray mass spectrometry

M. Tereza Fernandez, M. Manuela Silva, Lurdes Mira, M. Helena Florencio, Andy Gill, Keith R. Jennings

Research output: Contribution to journalArticlepeer-review

Abstract

Captopril, enalaprilat and lisinopril, angiotensin-converting enzyme (ACE) inhibitors, are effective HO. radical scavengers and seem to have some degree of metal binding capabilities. By metal chelation iron and copper may become inactive in radical generation or the antioxidant effect can be operative by site-specific scavenging. In order to clarify the ability of the ACE inhibitors to bind iron and copper, their interactions were investigated by spectrophotometry and electrospray ionisation mass spectrometry. The spectrophotometric results showed that when iron or copper was added to the ACE inhibitors a decrease of the absorbance at 211 nm was observed. Significant modifications of the spectra in the range 250-400 nm were also observed when copper was added. An association of the ACE inhibitors with iron or copper may be inferred from these studies. The electrospray mass spectra of captopril, enalaprilat and lisinopril, when copper was added, exhibited peaks attributed to the chelation of copper by the three ACE inhibitors, with a preference for 1:1 metal : ligand stoichiometry. The electrospray data also suggest that iron is not as effective as copper for the formation of metal : ligand complexes for captopril, enalaprilat and lisinopril.
Original languageEnglish
Pages (from-to)93-98
JournalJournal of Inorganic Biochemistry
Volume71
Issue number1-2
Publication statusPublished - 1998

Keywords / Materials (for Non-textual outputs)

  • Angiotensin-converting enzyme inhibitors
  • Metal-chelation
  • Electrospray mass spectrometry
  • Antioxidants

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