Relevance and isotopic assessment of hexose-6-phosphate recycling in micro-organisms

Some pathways of hexose-6-phosphate recycling - those involving a breakdown of the hexose skeleton through carbohydrate metabolism of micro-organisms were analyzed for both metabolic and isotopic effects. Two modes of recycli ng were proposed based on the degree of alteration of the hexose molecule t hrough the catabolic part of the cycle. Simulated operation of most of thes e pathways resulted in increased synthesis of hexose-6-phosphate and NADPH, and reduced the NADH and moreover the ATP synthesis within the carbohydrat e metabolism. A basic model for the quantitative assessment by means of iso topic studies of the processes of hexose-6-phosphate recycling is presented . The model was initially designed for the study of micro-organisms produci ng polysaccharides, but it can be extended to other situations. (C) 2000 El sevier Science B.V. All rights reserved.