A method for obtaining the 14C-isotope distribution in malate(C-2,3)

A method is described for the analysis of the isotope distribution in malate(C-2,3). In a single test-tube reaction, the inner carbon atoms of malate are enzymically converted to acetate and are stereospecifically incorporated into citrate as acetyl-CoA. A rapid method for obtaining the intramolecular isotope distribution in citrate(C-1,2) permits calculation of the isotope distribution and specific activity of the original malate carbon atoms. The error is less than 3%. This method is relevant to the recently reported problem of anomalous isotope distributions in the organic acids of C3 plants following short-term photosynthesis in 14CO2.