title: Stereospecificity of the enzymatic dehydrogenation in the biosynthesis of 3-ethylidene-L-azetidine-2-carboxylic acid from isoleucine by Streptomyces cacaoi.
abstract: (2RS,3S,4S)-[2-14C,4-3H]Isoleucine and (2S,3S,4R)-[U-14C,4-3H]isoleucine have been prepared by stereospecific syntheses. The addition of these substrates to Streptomyces cacaoi led to the isolation of polyoxins from which 3-ethylidene-L-azetidine-2-carboxylic acid was isolated by hydrolysis. The pro-R hydrogen at C-4 of isoleucine was lost and the pro-S hydrogen was retained in the biosynthesis of 3-ethylidene-L-azetidine-2-carboxylic acid. These results indicate that the enzymatic dehydrogenation of isoleucine to form 3-ethylidene-L-azetidine-2-carboxylic acid involves the antiperiplanar elimination of the hydrogen at C-3 and the pro-R hydrogen at C-4.
mesh_terms: D001383:Azetidinecarboxylic Acid / Q000031:analogs & derivatives / Q000096:biosynthesis; D002250:Carbon Radioisotopes; D007532:Isoleucine / Q000378:metabolism*; D011865:Radioisotope Dilution Technique; D013237:Stereoisomerism; D013302:Streptomyces / Q000378:metabolism*; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D007532:Isoleucine; D014316:Tritium; C010624:polyoximic acid; D001383:Azetidinecarboxylic Acid