ABSTRACT
The oxidative Weimberg pathway for the five-step pentose degradation to α-ketoglutarate is a key route for sustainable bioconversion of lignocellulosic biomass to added-value products and biofuels. The oxidative pathway from Caulobacter crescentus has been employed in in-vivo metabolic engineering with intact cells and in in-vitro enzyme cascades. The performance of such engineering approaches is often hampered by systems complexity, caused by non-linear kinetics and allosteric regulatory mechanisms. Here we report an iterative approach to construct and validate a quantitative model for the Weimberg pathway. Two sensitive points in pathway performance have been identified as follows: (1) product inhibition of the dehydrogenases (particularly in the absence of an efficient NAD+ recycling mechanism) and (2) balancing the activities of the dehydratases. The resulting model is utilized to design enzyme cascades for optimized conversion and to analyse pathway performance in C. cresensus cell-free extracts.
Subject(s)
Bacterial Proteins/genetics , Bioreactors , Caulobacter crescentus/genetics , Metabolic Engineering/methods , Models, Chemical , Bacterial Proteins/metabolism , Biofuels , Carbohydrate Metabolism/genetics , Caulobacter crescentus/enzymology , Computer Simulation , Hydro-Lyases/genetics , Hydro-Lyases/metabolism , Ketoglutaric Acids/metabolism , Metabolic Networks and Pathways/genetics , NADP/metabolism , Oxidation-Reduction , Oxidoreductases/genetics , Oxidoreductases/metabolism , Xylose/metabolismABSTRACT
Two supramolecular nanocapsules were generated by multi-component self-assembly of the novel bisphosphoric acid (R,R)-6 with suitable bis- and trisamidines. The resulting chiral, hydrogen-bonded capsules are stable even in polar media and at low concentrations and can be employed for the binding of C70-fullerene in solution.
