Manganese is also used in portland cement mixtures. Manganese is an important element for human health, essential for development, metabolism, and the antioxidant system. Nevertheless, excessive exposure or intake may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death and symptoms similar to Parkinson's disease. The classes of enzymes that have manganese cofactors is large and includes oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, lectins, and integrins. The reverse transcriptases of many retroviruses (though not lentiviruses such as HIV) contain manganese. The best-known manganese-containing polypeptides may be arginase, the diphtheria toxin, and Mn-containing superoxide dismutase (Mn-SOD).
Manganese(II) chloride Manganese(II) chloride Manganese(II) chloride describes a series of compounds with the formula MnCl(HO), where the value of x can be 0, 2, or 4. The tetrahydrate is the most common form of "manganese(II) chloride" and is the tetrahydrate with the formula MnCl·4HO. The anhydrous form and a dihydrate MnCl·2HO are also known. Like many Mn(II) species, these salts are pink, with the paleness of the color being characteristic of transition metal complexes with high spin d configurations. Manganese chloride is produced by treating manganese(IV) oxide with concentrated hydrochloric acid. This reaction was once used for the manufacture of chlorine. By