From Proteopediaproteopedia link
X ray structure of the complex between carbonic anhydrase II and LC inhibitors
[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
A sulfonamide derivative of the antihelmintic drug thiabendazole was prepared and investigated for inhibition of the zinc enzyme carbonic anhydrase CA (EC 126.96.36.199). Mammalian isoforms CA I-XIV and the nematode enzyme of Caenorhabditis elegans CAH-4b were included in this study. Thiabendazole-5-sulfonamide was a very effective inhibitor of CAH-4b and CA IX (K(I)s of 6.4-9.5nm) and also inhibited effectively isozymes CA I, II, IV-VII, and XII, with K(I)s in the range of 17.8-73.2nM. The high resolution X-ray crystal structure of its adduct with isozyme II evidenced the structural elements responsible for this potent inhibitory activity.
A thiabendazole sulfonamide shows potent inhibitory activity against mammalian and nematode alpha-carbonic anhydrases.,Crocetti L, Maresca A, Temperini C, Hall RA, Scozzafava A, Muhlschlegel FA, Supuran CT Bioorg Med Chem Lett. 2009 Mar 1;19(5):1371-5. Epub 2009 Jan 19. PMID:19186056
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.