structural:summarization, information:classification, structural:expansion
Biochemistry

Many classes of enzymes contain manganese cofactors including oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. Other enzymes containing manganese are arginase and a Mn-containing superoxide dismutase (Mn-SOD). Some reverse transcriptases of many retroviruses (although not lentiviruses such as HIV) contain manganese. Manganese-containing polypeptides are the diphtheria toxin, lectins, and integrins.

The oxygen-evolving complex (OEC), containing four atoms of manganese, is a part of photosystem II contained in the thylakoid membranes of chloroplasts. The OEC is responsible for the terminal photooxidation of water during the light reactions of photosynthesis, i.e., it is the catalyst that makes the O produced by plants.