The use of biocatalysis for the synthesis of high value added chemical building blocks derived from biomass is becoming an increasingly important application for future sustainable technologies. The synthesis of a higher value chemical from L-arabinose, the predominant monosaccharide obtained from sugar beet pulp, is demonstrated here via a transketolase and transaminase coupled reaction. Thermostable transketolases derived from Deinococcus geothermalis and Deinococcus radiodurans catalysed the synthesis of L-gluco-heptulose from L-arabinose and beta-hydroxypynwate at elevated temperatures with high conversions. beta-Hydroxypyruvate, a commercially expensive compound used in the transketolase reaction, was generated in situ from t-serine and alpha-ketoglutaric acid via a thermostable transaminase, also from Deinococcus geothermalis. The two steps were investigated and implemented in a one-pot system for the sustainable and efficient production of L-gluco-heptulose.