D-Glucaric (8accharFc) acid, the naturally occurring dicarboxylic acid aualogue of D-glucose, can support the growth of a variety of microorganisms

D-Glucaric (8accharFc) acid, the naturally occurring dicarboxylic acid aualogue of D-glucose, can support the growth of a variety of microorganisms (den Dooren de Jong, 1926), particularly grcherlchia coli and related enteric bacteria (Kay, 1926). Initial studies on the intermediary metabolism of D glucarate shoved that when 3. coli is grown In glucarate or galactarate, both resting-cell suspensions and cell-free axtracts from this culture can convert 1 mole of glucarate to 1 mole of pyruvate and unidentified products in the presence of areenfte (Blumenthal and Campbell, 1958). Later the first step in this conversion was shown to involve dehydration by D-glucarate dehydrase (Blumenthal, 1960), resulting in a yield of both 2-lceto-J-deoxyand 4-deoxy-5-ketoD-glucarate, the latter compound being the major product (Fish and Blumenthal, 1961). We now have evidence that two additional eusymee take part in the conversion of 1 mole of D-glucarate to 1 mole each of pyruvate and glycerate. These enzymes, which have bean partially purified from E. coli extracts, are ketodeoqglucarate aldolase (Fish and Blumenthal, 1963) and tartronate seuialdehyde reductase (D-glycerate 3-dehydrogeuaee). The entire sequence for the catabolism of D-glucarate is showu in Pig. 1. gvidence substantiating this mechanism has been gained through stoichiometric analysis (Table 1) of reactions employing the partially purified 9. & enzymes.