Although manganese is an important part of the oxygen evolving system in photosystem II and is, thus, of ultimate biological importance, its role in other enzymes remains poorly explored.


Manganese compounds are found in reductases, dioxygenases, phosphatases and oxidases.

The metal atoms in these compounds are generally bound by oxygen and nitrogen donors of the protein side chains. Manganese occurs in the oxidation state +II to +IV in such compounds.