Redox Reduction
Ion exchange
Enzymes
https://en.m.wikipedia.org/wiki/Oxidoreductase
Nucleophile
Cysteine Enzyme
Sulfur Sulfhydryl Thiol
Metallothionein
Metallothionein production is dependent on availability of the dietary minerals such as zinc, copper, and selenium, as well as the amino acids histidine and cysteine.
https://en.m.wikipedia.org/wiki/Metallothionein
https://en.m.wikipedia.org/wiki/Cysteine