[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.
The X-ray crystal structure of the fluorescent antitumor sulfonamide carbonic anhydrase (CA, EC, 126.96.36.199) inhibitor (4-sulfamoylphenylethyl)thioureido fluorescein (1) in complex with the cytosolic isoform hCA II is reported, together with a modeling study of the adduct of 1 with the tumor-associated isoform hCA IX. Its binding to hCA II is similar to that of other benzesulfonamides, with the ionized sulfonamide coordinated to the Zn2+ ion within the enzyme active site, and also participating in a network of hydrogen bonds with residues Thr199 and Glu106. The scaffold of 1 did not establish polar interactions within the enzyme active site but made hydrophobic contacts (<4.5 A) with Gln92, Val121, Phe131, Val135, Leu198, Thr199, Thr200, and Pro202. The substituted 3-carboxy-amino-phenyl functionality was at van der Waals distance from Phe131, Gly132, and Val135. The bulky tricyclic fluorescein moiety was located at the rim of the active site, on the protein surface, and strongly interacted with the alpha-helix formed by residues Asp130-Val135. All these interactions were preserved in the hCA IX-1 adduct, but the carbonyl moiety of the fluorescein tail of 1 participates in a strong hydrogen bond with the guanidine moiety of Arg130, an amino acid characteristic of the hCA IX active site. This may account for the roughly 2 times higher affinity of 1 for hCA IX over hCA II and may explain why in vivo the compound specifically accumulates only in hypoxic tumors overexpressing CA IX and not in the normal tissues. The compound is in clinical studies as an imaging tool for acute hypoxic tumors.
Carbonic anhydrase inhibitors: X-ray and molecular modeling study for the interaction of a fluorescent antitumor sulfonamide with isozyme II and IX.,Alterio V, Vitale RM, Monti SM, Pedone C, Scozzafava A, Cecchi A, De Simone G, Supuran CT J Am Chem Soc. 2006 Jun 28;128(25):8329-35. PMID:16787097
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Venta PJ, Welty RJ, Johnson TM, Sly WS, Tashian RE. Carbonic anhydrase II deficiency syndrome in a Belgian family is caused by a point mutation at an invariant histidine residue (107 His----Tyr): complete structure of the normal human CA II gene. Am J Hum Genet. 1991 Nov;49(5):1082-90. PMID:1928091
↑ Roth DE, Venta PJ, Tashian RE, Sly WS. Molecular basis of human carbonic anhydrase II deficiency. Proc Natl Acad Sci U S A. 1992 Mar 1;89(5):1804-8. PMID:1542674
↑ Soda H, Yukizane S, Yoshida I, Koga Y, Aramaki S, Kato H. A point mutation in exon 3 (His 107-->Tyr) in two unrelated Japanese patients with carbonic anhydrase II deficiency with central nervous system involvement. Hum Genet. 1996 Apr;97(4):435-7. PMID:8834238
↑ Shah GN, Bonapace G, Hu PY, Strisciuglio P, Sly WS. Carbonic anhydrase II deficiency syndrome (osteopetrosis with renal tubular acidosis and brain calcification): novel mutations in CA2 identified by direct sequencing expand the opportunity for genotype-phenotype correlation. Hum Mutat. 2004 Sep;24(3):272. PMID:15300855 doi:10.1002/humu.9266
↑ Briganti F, Mangani S, Scozzafava A, Vernaglione G, Supuran CT. Carbonic anhydrase catalyzes cyanamide hydration to urea: is it mimicking the physiological reaction? J Biol Inorg Chem. 1999 Oct;4(5):528-36. PMID:10550681
↑ Kim CY, Whittington DA, Chang JS, Liao J, May JA, Christianson DW. Structural aspects of isozyme selectivity in the binding of inhibitors to carbonic anhydrases II and IV. J Med Chem. 2002 Feb 14;45(4):888-93. PMID:11831900
↑ Alterio V, Vitale RM, Monti SM, Pedone C, Scozzafava A, Cecchi A, De Simone G, Supuran CT. Carbonic anhydrase inhibitors: X-ray and molecular modeling study for the interaction of a fluorescent antitumor sulfonamide with isozyme II and IX. J Am Chem Soc. 2006 Jun 28;128(25):8329-35. PMID:16787097 doi:http://dx.doi.org/10.1021/ja061574s