Manganese Based Catalase from Lactobacillus Plantarum
Catalases are important antioxidants. The enzymes catalyze the disproportionation of hydrogen peroxide to water and O2.
2 H2O2 → O2 + 2 H2O
The catalytic centers can either contain an iron haem group or a manganese based unit. An example for the latter group of enzymes is the structurally well characterized catalase from Lactobacillus Plantarum.
The hexameric units of the protein are connected using Ca2+ ions. Each subunit contains a dimeric manganese center, which is accessible via a polar substrate channel.
The manganese atoms are connected by a µ-1,3-bound glutamate residue as well as by two water molecules. Their coordination spheres are completed by histidine. In contrast to other structurally characterized manganese based catalases, the active site of the catalase from Lactobacillus plantarum contains an arginine residue and a glutamine residue, which are responsible for the proper orientation of the substrate.