Photoinactivation of trypanothione reductase and glutathione reductase by A1-phthalocyanine tetrasulfonate and hematoporphyrin

Regina Kliukiené, Audrone Maroziené, Narimantas Cénas, Katja Becker, John S. Blanchard

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The irradiation of Trypanosoma congolense trypanothione reductase (TR), human erythrocyte (HGR) and yeast glutathione reductase (YGR) with visible light in the presence of A1-phthalocyanine tetrasulfonate (A1PcS4) or hematoporphyrin (Hp) caused a time-dependent inactivation of these enzymes. TR was inactivated more rapidly than either HGR or YGR. Half-maximal rates of inactivation were determined in the presence of 100 μM Hp and 1.4-17 μM A1PcS4. The photosensitized irradiation modified the disulfide substrate-binding sites of these enzymes, most likely the conserved catalytic histidine residue. In the dark, A1PcS4 acted as a reversible inhibitor competitive with the disulfide substrate of TR and HGR. These findings suggest the possible use of photosensitized irradiation for preventing the transmission of trypanosomiasis by blood transfusion.

Original languageEnglish (US)
Pages (from-to)629-632
Number of pages4
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - Jan 17 1996


ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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