Biomaterial Database

Anion inhibition of CO2 hydration catalyzed by human carbonic anhydrase II. Mechanistic implications. 1984

L Tibell, and C Forsman, and I Simonsson, and S Lindskog

Five monovalent anions, I-, N3-, SCN-, NCO- and Au(CN)2-, were investigated as inhibitors of CO2 hydration catalyzed by human carbonic anhydrase II (carbonate hydro-lyase, EC 4.2.1.1). Predominantly uncompetitive inhibition patterns were observed at pH near 9 in all cases. While Dixon plots of Km/V vs. inhibitor concentration were linear, all the investigated anions except NCO- gave nonlinear Dixon plots of 1/V vs. inhibitor concentration. The anion SCN- was also tested at pH 7.4 and 6.4. Essentially noncompetitive patterns of inhibition of CO2 hydration were obtained at both these pH values. These results are analyzed in terms of two rivaling mechanism models, a kinetic scheme originally proposed by Steiner et al. (Steiner, H., Jonsson, B.-H. and Lindskog, S. (1975) Eur. J. Biochem. 59, 253-259) and a rapid-equilibrium kinetic scheme proposed by Pocker and Deits (Pocker, Y. and Deits, T.L. (1982) J. Am. Chem. Soc. 104, 2424-2434). It is concluded that the observed steady-state inhibition patterns are compatible with both models, but that discriminatory data, strongly favouring the model of Steiner et al., are available in the literature.

UI	MeSH Term	Description	Entries
D007454	Iodides	Inorganic binary compounds of iodine or the I- ion.	Iodide
D007527	Isoenzymes	Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics.	Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D002245	Carbon Dioxide	A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.	Carbonic Anhydride,Anhydride, Carbonic,Dioxide, Carbon
D002256	Carbonic Anhydrases	A family of zinc-containing enzymes that catalyze the reversible hydration of carbon dioxide. They play an important role in the transport of CARBON DIOXIDE from the tissues to the LUNG. EC 4.2.1.1.	Carbonate Dehydratase,Carbonic Anhydrase,Anhydrases, Carbonic,Dehydratase, Carbonate
D002257	Carbonic Anhydrase Inhibitors	A class of compounds that reduces the secretion of H+ ions by the proximal kidney tubule through inhibition of CARBONIC ANHYDRASES.	Carbonate Dehydratase Inhibitor,Carbonate Dehydratase Inhibitors,Carbonic Anhydrase Inhibitor,Carboxyanhydrase Inhibitor,Carboxyanhydrase Inhibitors,Anhydrase Inhibitor, Carbonic,Dehydratase Inhibitor, Carbonate,Inhibitor, Carbonate Dehydratase,Inhibitor, Carbonic Anhydrase,Inhibitor, Carboxyanhydrase,Inhibitors, Carbonate Dehydratase,Inhibitors, Carbonic Anhydrase,Inhibitors, Carboxyanhydrase
D003485	Cyanates	Organic salts of cyanic acid containing the -OCN radical.	Cyanate
D006046	Gold	A yellow metallic element with the atomic symbol Au, atomic number 79, and atomic weight 197. It is used in jewelry, goldplating of other metals, as currency, and in dental restoration. Many of its clinical applications, such as ANTIRHEUMATIC AGENTS, are in the form of its salts.
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations