[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 crystal structure of a human carbonic anhydrase II (CAII) variant, cis-proline-202-->alanine (P202A), has been determined at 1.7-A resolution, indicating that the wild-type geometry, including the cis-peptidyl linkage, is retained upon substitution of proline by alanine. The CO2 hydrase activity and affinity for sulfonamide inhibitors of P202A CAII are virtually identical to those of wild type. However, the substitution of cis-alanine for cis-proline decreases the stability of the folded state by approximately 5 kcal mol-1 relative to both the unfolded state and an equilibrium intermediate in guanidine hydrochloride-induced denaturation. This destabilization can be attributed mainly to the less favorable cis/trans equilibrium of Xaa-alanine bonds compared to Xaa-proline bonds in the denatured state although other factors, including increased conformational entropy of the denatured state and decreased packing interactions in the native state, also contribute to the observed destabilization. The high catalytic activity of P202A CAII illustrates that unfavorable local conformations are nonetheless endured to satisfy the precise structural requirements of catalysis and ligand binding in the CAII active site.
Structure and energetics of a non-proline cis-peptidyl linkage in a proline-202-->alanine carbonic anhydrase II variant.,Tweedy NB, Nair SK, Paterno SA, Fierke CA, Christianson DW Biochemistry. 1993 Oct 19;32(41):10944-9. PMID:8218160
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
↑ Tweedy NB, Nair SK, Paterno SA, Fierke CA, Christianson DW. Structure and energetics of a non-proline cis-peptidyl linkage in a proline-202-->alanine carbonic anhydrase II variant. Biochemistry. 1993 Oct 19;32(41):10944-9. PMID:8218160