Phenothiazine Radicals Inactivate Trypanosoma cruzi Dihydrolipoamide Dehydrogenase: Enzyme Protection by Radical Scavengers

Authors: Gutiérrez-Correa, José1; Krauth-Siegel, R. Luise2; Stoppani, Andrés O.M.1

Source: Free Radical Research, Volume 37, Number 3, 1 January 2003 , pp. 281-291(11)

Publisher: Informa Healthcare

Buy & download fulltext article:

OR

Price: $43.96 plus tax (Refund Policy)

Abstract:

Phenothiazine cation radicals (PTZ+•) irreversibly inactivated Trypanosoma cruzi dihydrolipoamide dehydrogenase (LADH). These radicals were obtained by phenothiazine (PTZ) peroxidation with myeloperoxidase (MPO) or horseradish peroxidase (HRP/H2O2) systems. LADH inactivation depended on PTZ structure and incubation time. After 10 min incubation of LADH with the MPO-dependent systems, promazine, trimeprazine and thioridazine were the most effective; after 30 min incubation, chlorpromazine, prochlorperazine and promethazine were similarly effective. HRP-dependent systems were equally or more effective than the corresponding MPO-dependent ones. Chloro, trifluoro, propionyl and nitrile groups at position 2 of the PTZ ring significantly decreased molecular activity, specially with the MPO/H2O2 systems. Comparison of inactivation values for LADH and T. cruzi trypanothione reductase demonstrated a greater sensitivity of LADH to chlorpromazine and perphenazine and a 10-fold lower sensitivity to promazine, thioridazine and trimeprazine. Alkyl-amino, alkyl-piperidinyl or alkyl-piperazinyl groups at position 10 modulated PTZ activity to a limited degree. Production of PTZ+• radicals was demonstrated by optical and ESR spectroscopy methods. PTZ+• radicals stability depended on their structure as demonstrated by promazine and thioridazine radicals. Thiol compounds such as GSH and N-acetylcysteine, l-tyrosine, l-tryptophan, the corresponding peptides, ascorbate and Trolox, prevented LADH inactivation by the MPO/H2O2/thioridazine system, in close agreement with their action as PTZ+• scavengers. NADH (not NAD+) produced transient protection of LADH against thioridazine and promazine radicals, the protection kinetics being affected by the relatively fast rate of NADH oxidation by these radicals. The role of the observed effects of PTZ radicals for PTZ cytotoxicity is discussed.

Keywords: Cation radical; Dihydrolipoamide dehydrogenase; Horseradish peroxidase; Myeloperoxidase; Phenothiazines; Trypanosoma cruzi

Document Type: Research Article

DOI: http://dx.doi.org/10.1080/1071576021000046622

Affiliations: 1: Bioenergetics Research Centre, School of Medicine, University of Buenos Aires, Paraguay 2155, 1121- Buenos Aires, Argentina 2: Biochemie-Zentrum, Heidelberg University, Im Neuenheimer Feld 328, 69120- Heidelberg, Germany

Publication date: January 1, 2003

More about this publication?
Related content

Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content

Text size:

A | A | A | A
Share this item with others: These icons link to social bookmarking sites where readers can share and discover new web pages. print icon Print this page