Spin Adducts of Superoxide, Alkoxyl, and Lipid-Derived Radicals with EMPO and Its Derivatives
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Klaus Stolze
Abstract
The compound 5-(ethoxycarbonyl)-5-methyl-1-pyrroline Noxide (EMPO) is a hydrophilic cyclic nitrone spin trap, which, in contrast to DMPO, forms a relatively stable superoxide adduct (t1/2=8.6 min) with an EPR spectrum similar to the respective DMPO adduct. In order to find the optimal degree of lipophilicity of this novel type of spin trap with respect to the detection of radicals formed during lipid peroxidation, the ethoxy group of EMPO was replaced by alkoxy substituents of increasing chain length, leading to the methoxy (MeMPO), 1-propoxy (PrMPO), 1-butoxy (BuMPO), and 1-octyloxy (OcMPO) derivatives of EMPO. The stability of their superoxide adducts was found to be strongly dependent on the size of the alkoxycarbonyl group. Increasing chain length of the alkoxyl substituent decreased the stability of alkoxyl radical adducts of MeMPO, EMPO, and PrMPO, but increased the stability of OcMPO adducts. The stability of alkoxyl radical adducts of BuMPO, on the other hand, were practically independent of the size of the alkoxyl group. Detection of lipid alkoxyl radicals formed by peroxidizing linoleic acid in a stationary system was therefore only possible with the most lipophilic spin trap, OcMPO. However, with the more hydrophilic spin traps MeMPO, EMPO, PrMPO, and BuMPO optimal EPR signal intensity could be obtained when a slowflow system was used. Thus, within this series EMPO is the best spin trap for the detection of superoxide; OcMPO, on the other hand, is most suitable for the detection of lipid alkoxyl radicals.
Copyright © 2002 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Nobuhiko Katunuma: An Outstanding Scientific and Professional Career of a Warm-Hearted Person. Reflections on the Occasion of his 75th Birthday
- Structural and Functional Diversity of Connexin Genes in the Mouse and Human Genome
- Congopain from Trypanosoma congolense: Drug Target and Vaccine Candidate
- Biosynthesis of Lysosomal Proteinases in Health and Disease
- Calpain Function in the Differentiation of Mesenchymal Stem Cells
- Ku Antigen Supports Termination of Mammalian rDNA Replication by Transcription Termination Factor TTF-I
- Thyroid Stimulating Hormone Upregulates Secretion of Cathepsin B from Thyroid Epithelial Cells
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- Altered Storage of Proteases in Mast Cells from Mice Lacking Heparin: A Possible Role for Heparin Carboxypeptidase A Processing
- Clustering-Induced Signaling of CEACAM1 in PC12 Cells
- Spin Adducts of Superoxide, Alkoxyl, and Lipid-Derived Radicals with EMPO and Its Derivatives
- Glutathione S-Transferase of the Malarial Parasite Plasmodium falciparum: Characterization of a Potential Drug Target
- Analysis of the Structural Determinants for RNA Binding of the Human Protein AUF1/hnRNP D
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- Amyloid Fibril Formation by Human Stefin B in vitro: Immunogold Labelling and Comparison to Stefin A
- Lysosomal Peptidases and Glycosidases in Rheumatoid Arthritis
