Directed immobilisation of modificated galactitol-dehydrogenase on gold electrodes for electrochemical cofactor regeneration

摘要

Biofunctionalisation of metal surfaces is widely used in the field of analytical applications (1-7) especially in clinical diagnostics or bio fuel cells (8-10). But electroenzymatic reactions also play an important role for preparative applications as for enantiomerically pure fine chemicals (11, 12) or as important intermediates in the pharmaceutical industry. For this case, dehydrogenases represent an important class of enzymes in biotechnological processes due to their enantioselective oxidative and reductive catalytic properties (13, 14). For example, galactitol dehydrogenase (GatDH) oxidizes a variety of polyvalent aliphatic alcohols and polyols to the corresponding ketones and ketoses, respectively, and in the reverse reaction it reduces ketones with high stereoselectivity yielding the corresponding S-configurated alcohols (15, 16). These properties make GatDH a biocatalyst of biotechnical significance, e.g., for producing rare sugars and chiral alcohols by racemic resolution or by reduction of ketones, respectively. For preparative syntheses only catalytic amounts of the cofactor NAD+/NADH are required as the cofactor can be enzymatically recycled according to established methods (17-19).