Metallothioneins have a high content of cysteine residues that bind various heavy metals. By cadmium. Contains 4 disulfide bonds. The measured mass is that of apo-metallothionein with intact disulfide bonds. The measured mass is that of apo-metallothionein treated with acid to cleave disulfide bonds. The measured mass is that of metallothionein with intact disulfide bonds chelating one cadmium ion. The measured mass is that of metallothionein with intact disulfide bonds chelating 2 cadmium ions. Belongs to the metallothionein superfamily. Type 8 family.