The enzyme mannonate dehydratase () catalyzes the chemical reaction
This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is <small>D</small>-mannonate hydro-lyase (2-dehydro-3-deoxy-<small>D</small>-gluconate-forming). Other names in common use include mannonic hydrolase, mannonate hydrolyase, altronic hydro-lyase, altronate hydrolase, <small>D</small>-mannonate hydrolyase, and <small>D</small>-mannonate hydro-lyase. This enzyme participates in pentose and glucuronate interconversions.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code .