Old Yellow Enzyme-Catalyzed Dehydrogenation of Saturated Ketones

Enzymes from extremophiles have always been of great interest for biotechnology because of their ruggedness against various stress factors. We have isolated, cloned, heterologously expressed and characterized a thermostable old yellow enzyme (OYE) from Geobacillus kaustophilus. In addition to the expected 'enone' reduction, GkOYE also catalyzes the reverse reaction, i.e., the desaturation of C-C bonds adjacent to a carbonyl to give the corresponding alpha,beta-unsaturated ketone. The reaction proceeds at the expense of molecular oxygen without the need for a nicotinamide cofactor and represents an environmentally benign alternative to known chemical dehydrogenation methods.