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dc.contributor.authorFrick, G. Peter
dc.contributor.authorBlinder, Lyubov
dc.contributor.authorGoodman, H. Maurice
dc.date2022-08-11T08:10:05.000
dc.date.accessioned2022-08-23T16:54:42Z
dc.date.available2022-08-23T16:54:42Z
dc.date.issued1988-03-05
dc.date.submitted2008-08-15
dc.identifier.citationJ Biol Chem. 1988 Mar 5;263(7):3245-9.
dc.identifier.issn0021-9258 (Print)
dc.identifier.pmid3125177
dc.identifier.urihttp://hdl.handle.net/20.500.14038/42561
dc.description.abstractLeucine was oxidized by rat adipose tissue at a rate which was not limited by the activity of branched chain amino acid transaminase since high concentrations (10 mM) of [1-14C]leucine and its transamination product, alpha-keto[1-14C]isocaproate, were oxidized at similar rates. Despite the apparent abundance of transaminase activity, however, [1-14C]valine was oxidized at only 10 to 25% of the rate of its transamination product, alpha-keto[1-14C]isovalerate. The net rate at which [1-14C] valine was transaminated by intact tissues was estimated as the sum of the rates of 14CO2 production and alpha-ketoiso[1-14C]valerate release into the medium. Transamination did not limit the rate of valine oxidation since valine was transaminated 3 times as fast as it was oxidized. The rate of valine transamination increased 18-fold when its concentration was raised 100-fold, but the fraction of [1-14C]valine oxidized to 14CO2 remained constant over the range of incubation conditions studied. The oxidation/transamination ratio for leucine was also constant and exceeded the oxidation/transamination ratio for valine unless valine oxidation was stimulated, either by the addition of glucose or leucine. Stimulation of valine oxidation did not increase its transamination but reduced the rate at which alpha-ketoisovalerate was released from the tissue. The faster oxidation of alpha-ketoisocaproate than of alpha-ketoisovalerate may be due to the activation of branched chain alpha-keto acid dehydrogenase by alpha-ketoisocaproate, but the alpha-keto acid oxidation rates do not fully account for the faster transamination of leucine than of valine.
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=3125177&dopt=Abstract">Link to Article in PubMed</a>
dc.relation.urlhttp://www.jbc.org/content/263/7/3245.full.pdf+html
dc.subject3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
dc.subjectAdipose Tissue
dc.subjectAnimals
dc.subjectCarbon Dioxide
dc.subjectEnzyme Activation
dc.subjectGlucose
dc.subjectKeto Acids
dc.subjectKetone Oxidoreductases
dc.subjectKinetics
dc.subjectLeucine
dc.subjectMale
dc.subjectMultienzyme Complexes
dc.subjectOxidation-Reduction
dc.subjectRats
dc.subjectTransaminases
dc.subjectValine
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleTransamination and oxidation of leucine and valine in rat adipose tissue
dc.typeJournal Article
dc.source.journaltitleThe Journal of biological chemistry
dc.source.volume263
dc.source.issue7
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/899
dc.identifier.contextkey579788
html.description.abstract<p>Leucine was oxidized by rat adipose tissue at a rate which was not limited by the activity of branched chain amino acid transaminase since high concentrations (10 mM) of [1-14C]leucine and its transamination product, alpha-keto[1-14C]isocaproate, were oxidized at similar rates. Despite the apparent abundance of transaminase activity, however, [1-14C]valine was oxidized at only 10 to 25% of the rate of its transamination product, alpha-keto[1-14C]isovalerate. The net rate at which [1-14C] valine was transaminated by intact tissues was estimated as the sum of the rates of 14CO2 production and alpha-ketoiso[1-14C]valerate release into the medium. Transamination did not limit the rate of valine oxidation since valine was transaminated 3 times as fast as it was oxidized. The rate of valine transamination increased 18-fold when its concentration was raised 100-fold, but the fraction of [1-14C]valine oxidized to 14CO2 remained constant over the range of incubation conditions studied. The oxidation/transamination ratio for leucine was also constant and exceeded the oxidation/transamination ratio for valine unless valine oxidation was stimulated, either by the addition of glucose or leucine. Stimulation of valine oxidation did not increase its transamination but reduced the rate at which alpha-ketoisovalerate was released from the tissue. The faster oxidation of alpha-ketoisocaproate than of alpha-ketoisovalerate may be due to the activation of branched chain alpha-keto acid dehydrogenase by alpha-ketoisocaproate, but the alpha-keto acid oxidation rates do not fully account for the faster transamination of leucine than of valine.</p>
dc.identifier.submissionpathoapubs/899
dc.contributor.departmentDepartment of Physiology
dc.source.pages3245-9


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