Oxidation of 5-thio-2-nitrobenzoic acid, by the biologically relevant oxidants peroxynitrite anion, hydrogen peroxide and hypochlorous acid.
The modification of protein and non-protein thiols by oxidants including hydrogen peroxide (H(2)O(2)), peroxynitrite anion (ONOO(-)) and hypochlorous acid (HOCl) is well documented. Using an aromatic thiol, 5-thio-2-nitrobenzoic acid, and biologically relevant oxidants, we have identified higher oxidation states of sulfur including the sulfonic acid derivative and the disulfide S-oxide, a thiosulfinate, by HPLC and mass spectrometry. The initial reaction of ONOO(-) with 5-thio-2-nitrobenzoic acid yielded a transient red intermediate, the sulfenate anion. The red intermediate was observed when ONOO(-) and H(2)O(2) were used to oxidize 5-thio-2-nitrobenzoic acid and it persisted for several seconds at pH 7. HOCl oxidized the disulfide, 5,5'dithiobis(2-nitrobenzoic acid) to the corresponding sulfonic acid and no additional products were detected. Using this system, we can directly compare the thiol-oxidizing abilities of several oxidants. Because 5-thio-2-nitrobenzoic acid is the product of the reaction of Ellman's reagent with protein thiols, a detailed study of its stability in biological matrices where oxidants may be generated is warranted.
Landino
Lisa M
LM
Department of Chemistry, The College of William and Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA. lmland@wm.edu
Mall
Catherine B
CB
Nicklay
Joshua J
JJ
Dutcher
Sarah K
SK
Moynihan
Katherine L
KL
D000838:Anions / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006997:Hypochlorous Acid / Q000737:chemistry*; D013058:Mass Spectrometry; D015394:Molecular Structure; D009579:Nitrobenzoates / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000737:chemistry*; D013434:Sulfenic Acids / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013997:Time Factors
D000838:Anions; D009579:Nitrobenzoates; D016877:Oxidants; D013434:Sulfenic Acids; D013438:Sulfhydryl Compounds; D030421:Peroxynitrous Acid; C011136:thionitrobenzoic acid; D006997:Hypochlorous Acid; D006861:Hydrogen Peroxide