Cyclohexane-1,2-dione hydrolase: A new tool to degrade alicyclic compounds

Cyclic alcohols Cyclohexane-1.2-dione hydrolase Thiamine diphosphate Flavoenzyme Alicyclic alcohols are naturally occurring compounds wh ich can be degraded by microorgan isms via cleavage of the ring CC bond. DenitrifyingAzoarcus sp. strain 22Lin grows on cyclohexane-l .2-diol which serves as electron donor and carbon source. The diol is converted to cyclohexane-l.2-dione followed by hydrolysis to the corresponding semialdehyde and oxidation to adipate. The latter two reactions are catalyzed by the thiamine diphosphate-dependent llavoenzyme cyciohexane-1.2-dione hydrolase. the first a-ketolase known so far. Biochemical and structural properties of this new member of the thiamine diphosphate enzyme family will be presented.