The Formation of Z-Keto-3-deoxyheptonic Acid in Extracts of Escherichia coli B

In the preceding paper (I), evidence concerning the proof of structure of 2-keto-3-deoxyheptonic acid was presented and it was indicated that this compound is a major product of ribose 5-phosphate metabolism in extracts of Escherichia coli strain B. This report is concerned with the enzymic synthesis of 2-keto-3deosyheptonic acid in extracts of Escherichia coli strain B and is the first direct observation of the biosynthesis of this compound. It is suggested that 2-keto-3-deosyheptonic acid arises from erythrose 4-phosphate and phosphoryl-enolpyruvate. The condensation product, presumed to be 2-keto-3-deoxy-7-phosphoheptonic acid is then dephosphorylated, yielding 2-keto-3-deoxyheptonic acid. This pathway of 2-keto-3-deoxyheptonic acid synthesis is in accord with the observations reported by Srinivasan et al. (2) on the biosynthesis of 2-keto-3-deoxy-7-phosphoheptonic acid which has been demonstrated as an intermediate in the formation of shikimic acid.