CHARACTERIZATION OF A REVERSE GYRASE FROM THE EXTREMELY THERMOPHILIC HYDROGEN-OXIDIZING EUBACTERIUM CALDEROBACTERIUM-HYDROGENOPHILUM

Reverse gyrase was isolated from an extremely thermophilic hydrogen-ox idizing eubacterium Calderobacterium hydrogenophilum. The enzyme catal yses the introduction of positive supercoils into the covalent closed DNA and requires ATP or dATP for its activity. So far, reverse gyrase has been purified to homogeneity only from thermophilic archaebacteria . Reverse gyrase from C. hydrogenophilum such as the archaebacterial e nzymes is a monomeric protein and has a molecular mass between 115 and 120 kDa. The optimal reaction temperature is 90-degrees-C and the the rmostability of this reverse gyrase is remarkable. The enzyme retains more than 95% of the activity after 40 min of incubation at 100-degree s-C.