The cofactor Mg2+ - A key switch for effective continuous enzymatic production of GDP-mannose using recombinant GDP-mannose pyrophosphorylase

Article abstract of DOI:10.1016/S0008-6215(97)10095-7

The aim of the presented work is the chemoenzymatic synthesis of GDP- mannose (GDP-Man). Mannose-1-phosphate (Man-1-P) is synthesised by a very convenient chemical method and is activated with GTP and recombinant GDP- mannose pyrophosphorylase (GDP-Man PP) to give GDP-Man. The productivity of the process is improved using reaction engineering techniques. Detailed kinetic studies, modelling of the reaction and simulations of different reaction systems revealed that besides a strong product 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 gL^-1 d^-1 and an enzyme consumption of 0.9 Ug^-1, which means a six-fold improvement related to batch synthesis.