4n16
From Proteopedia
Structure of cholate bound to human carbonic anhydrase II
Structural highlights
Disease[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.[1] [2] [3] [4] [5] Function[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.[6] [7] Publication Abstract from PubMedThe carbonic anhydrases (CAs) are a family of mostly zinc metalloenzymes that catalyze the reversible hydration/dehydration of CO2 into bicarbonate and a proton. Human isoform CA II (HCA II) is abundant in the surface epithelial cells of the gastric mucosa, where it serves an important role in cytoprotection through bicarbonate secretion. Physiological inhibition of HCA II via the bile acids contributes to mucosal injury in ulcerogenic conditions. This study details the weak biophysical interactions associated with the binding of a primary bile acid, cholate, to HCA II. The X-ray crystallographic structure determined to 1.54 A resolution revealed that cholate does not make any direct hydrogen-bond interactions with HCA II, but instead reconfigures the well ordered water network within the active site to promote indirect binding to the enzyme. Structural knowledge of the binding interactions of this nonsulfur-containing inhibitor with HCA II could provide the template design for high-affinity, isoform-specific therapeutic agents for a variety of diseases/pathological states, including cancer, glaucoma, epilepsy and osteoporosis. Structural elucidation of the hormonal inhibition mechanism of the bile acid cholate on human carbonic anhydrase II.,Boone CD, Tu C, McKenna R Acta Crystallogr D Biol Crystallogr. 2014 Jun;70(Pt 6):1758-63. doi:, 10.1107/S1399004714007457. Epub 2014 May 30. PMID:24914985[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Carbonate dehydratase | Human | Boone, C D | McKenna, R | Cholate | Cholic acid | Lyase
