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rdf:type |
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lifeskim:mentions |
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pubmed:dateCreated |
1991-7-3
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pubmed:abstractText |
Two new alkylating reagents, chloro- and bromo-acetylphosphonate, were found to be very effective thiol-blocking reagents. The pH-dependence of the reaction of BAP with 2,4-dinitrothiophenol (25 degrees C, I 0.5) shows a tailing bell-shaped curve (with a plateau at high pH) characteristic of two ionizing groups: the thiol group (pKa 3.2) and the phosphonate group (pKa2 4.6). The rate constant for the reaction of the monoanionic inhibitor with dinitrothiophenolate (k2 = 7 M-1.s-1) is 120 times larger than that of the dianionic species. The haloacetylphosphonates were found to be irreversible inhibitors of glyceraldehyde-3-phosphate dehydrogenase from a variety of sources. They react with the active-site thiol group (Cys-149) and are half-site reagents with yeast glyceraldehyde-3-phosphate dehydrogenase. Thus, when two of the identical four subunits are modified the enzyme is catalytically inactive. The effects of pH (7-10), 2H2O and NAD+ on the reaction with the yeast enzyme were examined in detail. NAD+ enhances the alkylation rates. The second-order rate constant does not show a simple sigmoidal dependence on pH but rather a tailing bell-shaped curve (pKa 7.0 and 8.4) qualitatively similar to that obtained with dinitrothiophenol. There is no significant solvent isotope effect on the limiting rate constants and a normal isotope effect on the two pKa values. The results are consistent with the more reactive enzyme species containing a thiolate and an acidic group that may either donate a proton to the dianionic haloacetylphosphonate or orient the inhibitor.
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pubmed:grant |
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-1253620,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-13084599,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-13084625,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-169882,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-2039453,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-2271518,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-2340265,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-235434,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-23783,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-2388,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-2659073,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-375973,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-385052,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4296412,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4326081,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4332597,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4339949,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4361748,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4376943,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4568612,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4594141,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4594142,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-4817797,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-5084801,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-5432063,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-7085642,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2039452-791285
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
0264-6021
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
1
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pubmed:volume |
275 ( Pt 3)
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
767-73
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:2039452-2,4-Dinitrophenol,
pubmed-meshheading:2039452-Alkylation,
pubmed-meshheading:2039452-Dinitrophenols,
pubmed-meshheading:2039452-Glyceraldehyde-3-Phosphate Dehydrogenases,
pubmed-meshheading:2039452-Hydrogen-Ion Concentration,
pubmed-meshheading:2039452-Indicators and Reagents,
pubmed-meshheading:2039452-Kinetics,
pubmed-meshheading:2039452-NAD,
pubmed-meshheading:2039452-Organophosphorus Compounds,
pubmed-meshheading:2039452-Saccharomyces cerevisiae,
pubmed-meshheading:2039452-Thermodynamics
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pubmed:year |
1991
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pubmed:articleTitle |
Alkylation of glyceraldehyde-3-phosphate dehydrogenase with haloacetylphosphonates. An unusual pH-dependence.
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pubmed:affiliation |
Department of Chemistry, Tulane University, New Orleans, LA 70118.
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pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, U.S. Gov't, P.H.S.
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