Succinic acid labelled with isotopic

In this connection it is of interest that Buchanan and coworkers demonstrated that isotopic acetoacetate (CH3 C 0-CH2 C 00H) and acetate (CH3-C OOH) are oxidized in kidney by way of the tricarboxylic cycle. In several experiments of this type, a-ketoglutarate, fumarate and succinate were isolated after incubation with isotopic acetoacetate or acetate. The isolated acids were found to contain sufficient excess of isotope to warrant the belief that acetoacetate and acetate are oxidized in kidney to a major extent by way of the tricarboxylic cycle. A similar result with carboxyl-labelled acetate has been obtained by Weinhouse and coworkers. ... 

Classical biosynthetic studies with C-labeled compounds and later with stable isotopes established that nonactic acid is derived from two acetates (or malonates), succinate and propionate (Fig. 3d) (21). Feeding studies with 36 (Fig. 3e) has shown that the first committed step of macrotetrolide biosynthesis is the coupling of the succinate unit with an acetate (or malonate) to give a-ketoadipate 40 (22). The late steps of non-actate biosynthesis (Fig. 3 g) were shown to involve the cycliza-tion of 42a into (-)-nonactate and 42b into (-l-)-nonactate, which... 

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