THE COFACTOR MG2- A KEY SWITCH FOR EFFECTIVE CONTINUOUS ENZYMATIC PRODUCTION OF GDP-MANNOSE USING RECOMBINANT GDP-MANNOSE PYROPHOSPHORYLASE( )

The aim of the presented work is the chemoenzymatic synthesis of GDP-m annose (GDP-Man). Mannose-l-phosphate (Man-l-P) is synthesised by a ve ry convenient chemical method and is activated with GTP and recombinan t GDP-mannose pyrophosphorylase (GDP-Man PP) to give GDP-Man, The prod uctivity of the process is improved using reaction engineering techniq ues. Detailed kinetic studies, modelling of the reaction and simulatio ns of different reaction systems revealed that besides a strong produc t inhibition the cofactor Mg2+ is a key switch for effective enzymatic synthesis. Using a two-stage cascade of enzyme membrane reactors, GDP -Man could be produced continuously with a space-time yield of 28 g L- 1 d(-1) and an enzyme consumption of 0.9 U g(-1), which means a six-fo ld improvement related to batch synthesis. (C) 1998 Elsevier Science L td. All rights reserved.