Phosphotriesterase (PTE) catalyzes the hydrolysis of organophosphate nerve agents, including the chemical warfare agents VX, soman, and sarin as well as the insecticide paraoxon. PTE exists as a homodimer with one active site per monomer. The active site is located next to a binuclear metal center, at the C-terminal end of a TIM alpha- beta barrel motif. The native enzyme contains two zinc ions at the active site however these can be replaced with other metals such as cobalt, cadmium, nickel or manganese and the enzyme remains active.
putative pre-16S rRNA nuclease YqgF and RuvX family. Escherichia coli YqgF has been shown to act as a pre-16S rRNA nuclease, presumably as a monomer. It is involved in the processing of pre-16S rRNA during ribosome maturation. The RuvX gene product from Mycobacterium tuberculosis was shown to act, in a dimeric form, as a Holliday junction resolvase (HJR). HJRs endonucleases specifically resolve Holliday junction DNA intermediates during homologous recombination. Holliday junctions are formed by the reciprocal exchange of strands between two DNA duplexes. HJRs occur in archaea, bacteria, and in the mitochondria of certain fungi; they may form homodimers and display structural similarity to RNase H and Hsp70.