The Enzymic Conversion of the Tartaric Acids to Oxaloacetic Acid

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Abstract
SUMMARY: Certain bacteria of the genus Pseudomonas attack the tartaric acids by means of inducible stereospecific dehydrases. Each dehydrase converts its specific isomeric substrate to oxaloacetic acid; in crude cell-free extracts the oxaloacetic acid is in turn converted to pyruvic acid, which accumulates. By treatment of the crude extracts with ethylenediaminetetraacetic acid (EDTA), substantial accumulations of oxaloacetic acid can be obtained from the meso- and d-tartaric acids, and assays for these two dehydrases, based on the accumulation of oxaloacetic acid in the presence of EDTA, have been developed. This procedure cannot be used to assay the l-tartaric acid dehydrase, which is itself very sensitive to EDTA. The patterns of inhibition of the three dehydrases by compounds stericaliy related to their substrates have been explored, and the findings are interpreted in terms of the minimal steric requirements for enzyme-substrate combination.