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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
2
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pubmed:dateCreated |
1984-5-10
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pubmed:abstractText |
The absorption coefficient of butyryl-CoA dehydrogenase from Megasphaera elsdenii at 450 nm is determined as 14.4 mM-1 X cm-1 in the CoA-free form and 14.2 mM-1 X cm-1 in the CoA-liganded form (both yellow). The latter value is considerably higher than the earlier published estimate. Phenazine ethosulphate offers great advantages over phenazine methosulphate as a coupling dye in the catalytic assay despite giving lower Vmax. values (506 min-1 as compared with 1250 min-1 under the conditions used). The phenazine ethosulphate assay is used to establish a pH optimum of 8.05 for oxidation of 100 microM-butyryl-CoA. The rates of oxidation of a range of straight-chain, branched-chain and alicyclic acyl thioesters are used to provide the following information. Only straight-chain acyl groups containing 4-6 carbon atoms are easily accommodated by the postulated hydrophobic pocket of the enzyme. C-3-substituted acyl-CoA thioesters are not oxidized at a significant rate, suggesting that the C-3 pro-S-hydrogen atom of straight-chain substrates is partially exposed to the solvent. Acyl-CoA thioesters with substitutions at C-2 are oxidized, though at a lower rate than their straight-chain counterparts. This implies that the C-2 pro-S-hydrogen atom of straight-chain substrates is partially exposed to the solvent. Saturated alicyclic carboxylic acyl-CoA thioesters with 4-7 carbon atoms in the ring are oxidized, with maximal activity for the cyclohexane derivative. This implies that optimal oxidation requires a true trans orientation of the two departing hydrogen atoms. The strain imposed by bound unsaturated alicyclic acyl thioesters strikingly perturbs the flavin visible-absorption spectrum, with the exception of the cyclohex-2-ene derivative, which forms a complex with similar spectral properties to those of the crotonyl-CoA complex. In the thiol moiety of thioester substrates the amide bond of N-acetylcysteamine is essential for both binding and catalysis. The adenosine structure contributes substantially to strong binding, but is less important in determining the catalytic rate.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-1275256,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-13130521,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-13163047,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-13295225,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-13650640,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-13840645,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-13899833,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-14086742,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-14166862,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-14269334,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-16590562,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-231392,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-4364030,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-4378783,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-4405086,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-4958817,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-570409,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-6261796,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-6278980,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-6712627,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-6930657,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-7067828,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-7126602,
http://linkedlifedata.com/resource/pubmed/commentcorrection/6712628-7240117
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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 |
Mar
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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 |
218
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
521-9
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pubmed:dateRevised |
2010-11-18
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pubmed:meshHeading |
pubmed-meshheading:6712628-Acyl Coenzyme A,
pubmed-meshheading:6712628-Binding Sites,
pubmed-meshheading:6712628-Butyryl-CoA Dehydrogenase,
pubmed-meshheading:6712628-Electron Transport,
pubmed-meshheading:6712628-Fatty Acid Desaturases,
pubmed-meshheading:6712628-Hydrogen-Ion Concentration,
pubmed-meshheading:6712628-Kinetics,
pubmed-meshheading:6712628-Macromolecular Substances,
pubmed-meshheading:6712628-Spectrophotometry,
pubmed-meshheading:6712628-Structure-Activity Relationship,
pubmed-meshheading:6712628-Substrate Specificity,
pubmed-meshheading:6712628-Veillonellaceae
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pubmed:year |
1984
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pubmed:articleTitle |
Butyryl-CoA dehydrogenase from Megasphaera elsdenii. Specificity of the catalytic reaction.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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