Source:http://linkedlifedata.com/resource/pubmed/id/17226929
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
1
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pubmed:dateCreated |
2007-1-17
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pubmed:abstractText |
Oxidized glutathione (GSSG) reacts with two molar equivalents of HOCl/OCl- (a neutrophil-derived oxidant and a common biocide) to form the dichloro (bis-N-chloro-gamma-l-glutamyl) derivative (NDG). The reaction of less than two molar equivalents of HOCl with GSSG does not yield the unsymmetrical monochloro derivative (NCG) but rather a stoichiometric amount of NDG and GSSG. This result is explained by a faster reaction of the second equivalent of HOCl with NCG than that of the first equivalent of HOCl with GSSG. The rates of reaction of GSSG2-, GSSG3-, and GSSG4- (successive deprotonation of the ammonium groups) have been investigated, and it is clear that GSSG2- is unreactive, whereas GSSG4- is about twice as reactive as GSSG3-. Accordingly, the following mechanism is proposed (constants for 5 degrees C): H+ + OCl- = HOCl, pK1 = -7.47; GSSG2- = GSSG3- + H+, pK2 = 8.5; GSSG3- = GSSG4- + H+, pK3 = 9.5; GSSG3- + HOCl --> NCG3- + H2O, k4 = 2.7(2) x 106 M-1 s-1; GSSG4- + HOCl --> NCG4- + H2O, k5 = 3.5(3) x 107 M-1 s-1; NCG3- --> NDG4- + H+, k6 = fast; and NCG4- + HOCl --> NDG4- + H2O, k7 = fast. At physiologic pH, the k4 pathway dominates. NDG decomposes at pH 7.4 in a first-order process with kdec = 4.22(1) x 10-4 s-1 (t1/2 = 27 min). Glutathione reductase (EC 1.6.4.2) is capable of catalyzing the reduction of NDG by NADPH. The only NDG-derived product that is observed (by NMR) after the reduction by NADPH is GSH. Thus, in the presence of the GOR/NADPH system, GSH is capable of redox buffering a 3/2 mol equiv of HOCl rather than a 1/2 mol equiv as previously assumed.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Jan
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pubmed:issn |
0893-228X
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
20
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
79-87
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pubmed:meshHeading |
pubmed-meshheading:17226929-Catalysis,
pubmed-meshheading:17226929-Chloramines,
pubmed-meshheading:17226929-Dimerization,
pubmed-meshheading:17226929-Glutathione,
pubmed-meshheading:17226929-Glutathione Reductase,
pubmed-meshheading:17226929-Hypochlorous Acid,
pubmed-meshheading:17226929-Kinetics,
pubmed-meshheading:17226929-Magnetic Resonance Spectroscopy,
pubmed-meshheading:17226929-Oxidation-Reduction,
pubmed-meshheading:17226929-Spectrophotometry, Ultraviolet
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pubmed:year |
2007
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pubmed:articleTitle |
Kinetics and mechanism of the oxidation of the glutathione dimer by hypochlorous Acid and catalytic reduction of the chloroamine product by glutathione reductase.
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pubmed:affiliation |
Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, Non-U.S. Gov't
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