5sz1
From Proteopedia
Carbonic anhydrase II in complex with 4-(2-methylphenyl)-benzenesulfonamide
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 PubMedCarbonic anhydrases (CAs) are implicated in a wide range of diseases, including the upregulation of isoforms CA IX and XII in many aggressive cancers. However, effective inhibition of disease-implicated CAs should minimally affect the ubiquitously expressed isoforms including CA I and II to improve directed distribution of the inhibitors to the cancer-associated isoforms and reduce side effects. Four benzenesulfonamide-based inhibitors were synthesized using the "tail approach" and display nM affinities for several CA isoforms. The crystal structures of the inhibitors bound to a CA IX-mimic and CA II are presented. Further in-silico modeling was performed with the inhibitors docked into CA I and XII to identify residues that contribute to or hinder their binding interactions. These structural studies demonstrate that active site residues lining the hydrophobic pocket, especially positions 92 and 131, dictate the positional binding and affinity of inhibitors and the tail groups modulate CA isoform specificity. Geometry optimizations were performed on each ligand in the crystal structures and showed the energetic penalties of the inhibitors' conformations were negligible compared to the gain of active site interactions. These studies further our understanding of obtaining isoform specificity when designing small molecule CA inhibitors. Structure activity relationships of benzenesulfonamide-based inhibitors towards carbonic anhydrase isoform specificity.,Bhatt A, Mahon BP, Cruzeiro VW, Cornelio B, Laronze-Cochard M, Ceruso M, Sapi J, Rance GA, Khlobystov AN, Fontana A, Roitberg A, Supuran CT, Mc Kenna R Chembiochem. 2016 Nov 18. doi: 10.1002/cbic.201600513. PMID:27860128[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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