Carbohydrate Metabolism by Pseudomonas Fluorescens

MacGee and Doudoroff (2) have gained evidence in support of the postulated scheme by recovering the product of Reaction 1 as a crystalline trisodium salt and establishing its structure as Na3-2-keto-3-deoxy-6-phosphogluconate+2Hz0. Extracts of Pseudomonas Jluorescens catalyze the cleavage of 6-PG to pyruvate and triose phosphate at a rate 10 times faster than the rate of 6-PG dehydrogenase action (3). Thus the reactions leading to pyruvate and triose phosphate formation may constitute a major pathway of 6-PG degradation in this organism. Fractionation of sonic extracts of P. Jluorescens has yielded a partially purified 6-PG dehydrase (4). This preparation did not produce pyruvate from 6-PG but converted 6-PG to 2-keto-3-deoxy-6phosphogluconate (KDPG) (Reaction 1). Ferrous ions and glutathione were required for activity. A second enzyme fraction has been obtained from P. jluorescens extracts which is inactive on 6-PG, but which catalyzes an aldolase type cleavage of KDPG to form pyruvate and n-glyceraldehyde-3-phosphate (Reaction 2). A combination of the 6-PG dehydrase with the enzyme fraction to be described converted 6-PG to pyruvate and n-glyceraldehyde-3-phosphate (G-3-P), as reported by Entner and Doudoroff (1).