{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,18]],"date-time":"2026-03-18T22:53:17Z","timestamp":1773874397010,"version":"3.50.1"},"reference-count":0,"publisher":"Portland Press Ltd.","issue":"3","content-domain":{"domain":["portlandpress.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1976,12,15]]},"abstract":"<jats:p>1. Normal human urine contains small amounts (&amp;lt; 4 mg\/g of creatinine) of 2-ethylhydracrylic acid, formed, we believe, by a previously undisclosed endogenous catabolic pathway for the oxidation of a newly described series of R metabolites of isoleucine. 2. Urinary excretion of 2-ethylhydracrylic acid is variably increased in defects of isoleucine oxidation at distal steps in the catabolic pathway (3-oxoacyl-CoA thiolase deficiency and methylmalonyl-CoA mutase deficiency) and is diminished when proximal steps of the oxidative pathway are blocked as in branched-chain oxo acid decarboxylase deficiency (\u2018maple-syrup-urine\u2019 disease). 3. Precursors of R-pathway metabolites [R(-)-2-methylbutyrate and 2-ethylacrylate] lead to increased 2-ethylhydracrylate excretion in the mammal(rat, rabbit and dog); the corresponding S metabolites [S(+)-2-methylbutyric acid and tiglic acid], when given in equimolar amounts, have little effect on its excretion, suggesting that little or no interconversion between S and R metabolites occurs in vivo. 4. Studies with 2H-labelled precursors indicate that conversion of R 2-methylbutyrate into 2-ethylhydracrylic acid occurs by a direct pathway (apparently via 2-ethylacrylic acid). 5. The further oxidation of 2-ethylhydracrylic acid to ethylmalonic acid was demonstrated, and may be analogous to S-metabolite oxidation via methyl malonate. 6. Valine metabolites do not interact with the R-isoleucine pathway under the conditions of these experiments in vivo.<\/jats:p>","DOI":"10.1042\/bj1600417a","type":"journal-article","created":{"date-parts":[[2015,8,10]],"date-time":"2015-08-10T20:04:42Z","timestamp":1439237082000},"page":"417-426","update-policy":"https:\/\/doi.org\/10.1042\/crossmark_policy","source":"Crossref","is-referenced-by-count":57,"title":["Demonstration of a new mammalian isoleucine catabolic pathway yielding an <i>R<\/i> series of metabolites"],"prefix":"10.1042","volume":"160","author":[{"given":"O A","family":"Mamer","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S S","family":"Tjoa","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"C R","family":"Scriver","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"G A","family":"Klassen","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"288","container-title":["Biochemical Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/160\/3\/417\/570685\/bj1600417a.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/160\/3\/417\/570685\/bj1600417a.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,11,26]],"date-time":"2021-11-26T17:13:37Z","timestamp":1637946817000},"score":1,"resource":{"primary":{"URL":"https:\/\/portlandpress.com\/biochemj\/article\/160\/3\/417\/10672\/Demonstration-of-a-new-mammalian-isoleucine"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1976,12,15]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1976,12,15]]}},"URL":"https:\/\/doi.org\/10.1042\/bj1600417a","relation":{},"ISSN":["0264-6021"],"issn-type":[{"value":"0264-6021","type":"print"}],"subject":[],"published":{"date-parts":[[1976,12,15]]}}}