From Proteopediaproteopedia link
Crystal structure of the complex between Carbonic Anhydrase II and anions
[CAH2_HUMAN] Defects in CA2 are the cause of osteopetrosis autosomal recessive type 3 (OPTB3) [MIM:259730]; also known as osteopetrosis with renal tubular acidosis, carbonic anhydrase II deficiency syndrome, Guibaud-Vainsel syndrome or marble brain disease. Osteopetrosis is a rare genetic disease characterized by abnormally dense bone, due to defective resorption of immature bone. The disorder occurs in two forms: a severe autosomal recessive form occurring in utero, infancy, or childhood, and a benign autosomal dominant form occurring in adolescence or adulthood. Autosomal recessive osteopetrosis is usually associated with normal or elevated amount of non-functional osteoclasts. OPTB3 is associated with renal tubular acidosis, cerebral calcification (marble brain disease) and in some cases with mental retardation.    
[CAH2_HUMAN] Essential for bone resorption and osteoclast differentiation (By similarity). Reversible hydration of carbon dioxide. Can hydrate cyanamide to urea. Involved in the regulation of fluid secretion into the anterior chamber of the eye. 
Publication Abstract from PubMed
Trithiocarbonate (CS32-) inhibits with low micromolar affinities several mammalian carbonic anhydrases, CAs, EC 220.127.116.11 [Innocenti et al., Bioorg. Med. Chem. Lett. 2009, 19, 1855]. Here we report the X-ray crystal structure of the hCA II-trithiocarbonate adduct. Trithiocarbonate is monodentately bound to the Zn(II) ion and makes several hydrogen bonds with Thr199 and two water molecules from the enzyme active site. Its binding is different from that of ureate, another small inhibitor isosteric with trithiocarbonate but somehow mimicks the binding of the SO(2)NH moiety present in the sulfonamide inhibitors and is similar to that of bicarbonate. Compounds incorporating this new zinc-binding group, CS2-, may thus lead to new classes of potent inhibitors.
Carbonic anhydrase inhibitors. X-ray crystal studies of the carbonic anhydrase II-trithiocarbonate adduct--an inhibitor mimicking the sulfonamide and urea binding to the enzyme.,Temperini C, Scozzafava A, Supuran CT Bioorg Med Chem Lett. 2010 Jan 15;20(2):474-8. Epub 2009 Nov 27. PMID:20005709
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.