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Modification of aldose reductase by S-nitrosoglutathione.
- Source :
-
Biochemistry [Biochemistry] 1997 Dec 16; Vol. 36 (50), pp. 15801-9. - Publication Year :
- 1997
-
Abstract
- Kinetic and structural changes in recombinant human aldose reductase (AR) due to modification by S-nitrosoglutathione (GSNO) were investigated. Incubation of the enzyme with 10-50 microM GSNO led to a time- and concentration-dependent inactivation of the enzyme, with a second-order rate constant of 0.087 +/- 0.009 M-1 min-1. However, upon exhaustive modification, 30-40% of the enzyme activity was retained. The non-inactivated enzyme displayed a 2-3-fold change in Km for NADPH and Km fordl-glyceraldehyde, whereas the Km for the lipid peroxidation product, 4-hydroxy-2-trans nonenal (HNE), was comparable to that of the untreated enzyme. The residual activity of the enzyme after GSNO treatment was less sensitive to inhibition by the active site inhibitor sorbinil or to activation by sulfate. Significantly higher catalytic activity was retained when the enzyme was modified in the presence of NADPH, suggesting relatively low reactivity of the E-NADPH complex with GSNO. The modification site was identified using site-directed mutants in which each of the solvent-exposed cysteines of the enzyme was replaced individually by serine. The mutant C298S was insensitive to GSNO, whereas the sensitivity of the mutants C303S and C80S was comparable to that of the wild-type enzyme. Electrospray ionization mass spectroscopy of the GSNO-modified enzyme revealed a major modified species (70% of the protein) with a molecular mass that was 306 Da higher than that of the untreated enzyme, which is consistent with the addition of a single glutathione molecule to the enzyme. The remaining 30% of the protein displayed a molecular mass that was not significantly different from that of the native enzyme. No nitrosated forms of the enzyme were observed. These results suggest that inactivation of AR by GSNO is due to the selective formation of a single mixed disulfide between glutathione and Cys-298 located at the NADP(H)-binding site of the enzyme.
- Subjects :
- Aldehyde Reductase antagonists & inhibitors
Aldehyde Reductase genetics
Aldehydes metabolism
Disulfides chemistry
Enzyme Activation
Enzyme Inhibitors pharmacology
Glutathione metabolism
Glutathione pharmacology
Glutathione Disulfide pharmacology
Glyceraldehyde metabolism
Humans
Imidazoles pharmacology
Iodoacetates pharmacology
Iodoacetic Acid
Kinetics
Mass Spectrometry
Mutagenesis, Site-Directed
NADP metabolism
Nitroso Compounds metabolism
Placenta enzymology
Recombinant Proteins metabolism
S-Nitrosoglutathione
Sulfates pharmacology
Aldehyde Reductase metabolism
Glutathione analogs & derivatives
Imidazolidines
Nitroso Compounds pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0006-2960
- Volume :
- 36
- Issue :
- 50
- Database :
- MEDLINE
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 9398310
- Full Text :
- https://doi.org/10.1021/bi9714722