Biomaterial Database

Enhancement of the catalytic activity of carbonic anhydrase III by phosphates. 1990

S R Paranawithana, and C K Tu, and P J Laipis, and D N Silverman

Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville 32610.

Phosphate and phosphate-containing buffers of physiological interest such as ATP and 3-phosphoglycerate were found to enhance catalysis by human carbonic anhydrase III (HCA III). Addition of phosphate caused an increase in both the catalyzed rate of hydration of CO2 at steady state measured by stopped-flow spectrophotometry and the exchange of 18O between CO2 and water at chemical equilibrium measured by mass spectrometry. The results are consistent with a mechanism in which phosphate enhances the transfer of protons between zinc-bound water at the active site and solution. Site-directed mutations to replace lysine 64 and arginine 67 in the active-site cavity resulted in greater enhancement by phosphate when compared with wild-type HCA III and showed that these basic residues are not essential as a binding site for phosphate. Phosphate did not enhance catalysis by HCA II.

UI	MeSH Term	Description	Entries
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.
D010103	Oxygen Isotopes	Stable oxygen atoms that have the same atomic number as the element oxygen, but differ in atomic weight. O-17 and 18 are stable oxygen isotopes.	Oxygen Isotope,Isotope, Oxygen,Isotopes, Oxygen
D010710	Phosphates	Inorganic salts of phosphoric acid.	Inorganic Phosphate,Phosphates, Inorganic,Inorganic Phosphates,Orthophosphate,Phosphate,Phosphate, Inorganic
D011994	Recombinant Proteins	Proteins prepared by recombinant DNA technology.	Biosynthetic Protein,Biosynthetic Proteins,DNA Recombinant Proteins,Recombinant Protein,Proteins, Biosynthetic,Proteins, Recombinant DNA,DNA Proteins, Recombinant,Protein, Biosynthetic,Protein, Recombinant,Proteins, DNA Recombinant,Proteins, Recombinant,Recombinant DNA Proteins,Recombinant Proteins, DNA
D002021	Buffers	A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.	Buffer
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
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
D016297	Mutagenesis, Site-Directed	Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.	Mutagenesis, Oligonucleotide-Directed,Mutagenesis, Site-Specific,Oligonucleotide-Directed Mutagenesis,Site-Directed Mutagenesis,Site-Specific Mutagenesis,Mutageneses, Oligonucleotide-Directed,Mutageneses, Site-Directed,Mutageneses, Site-Specific,Mutagenesis, Oligonucleotide Directed,Mutagenesis, Site Directed,Mutagenesis, Site Specific,Oligonucleotide Directed Mutagenesis,Oligonucleotide-Directed Mutageneses,Site Directed Mutagenesis,Site Specific Mutagenesis,Site-Directed Mutageneses,Site-Specific Mutageneses