Biomaterial Database

Solvent-mediated proton transfer in catalysis by carbonic anhydrase. 2007

David N Silverman, and Robert McKenna

Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida 32610, USA. silvermn@college.med.ufl.edu

Considerable attention has been focused on proton transfer through intervening water molecules in complex macromolecules of biological interest, such as bacteriorhodopsin, cytochrome c oxidase, and many others. Proton transfer in catalysis by carbonic anhydrase provides a useful model for the study of the properties of such proton translocations. High-resolution X-ray crystallography in combination with measurements of catalysis have revealed new details of this process. A prominent proton shuttle residue His64 shows evidence of structural mobility, which appears to enhance proton transfer between the active site and bulk solvent. Moreover, the properties of the imidazole side chain of His64, including its conformations and pK(a), are finely tuned by surrounding residues of the active-site cavity. The structure of a network of ordered solvent molecules located between His64 and the active site are also sensitive to surrounding residues. These features combine to provide efficient proton-transfer rates as great as 10(6) s(-1) necessary to sustain rapid catalysis.

UI	MeSH Term	Description	Entries
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D008958	Models, Molecular	Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.	Molecular Models,Model, Molecular,Molecular Model
D011522	Protons	Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.	Hydrogen Ions,Hydrogen Ion,Ion, Hydrogen,Ions, Hydrogen,Proton
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
D002384	Catalysis	The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.	Catalyses
D006639	Histidine	An essential amino acid that is required for the production of HISTAMINE.	Histidine, L-isomer,L-Histidine,Histidine, L isomer,L-isomer Histidine
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000409	Alanine	A non-essential amino acid that occurs in high levels in its free state in plasma. It is produced from pyruvate by transamination. It is involved in sugar and acid metabolism, increases IMMUNITY, and provides energy for muscle tissue, BRAIN, and the CENTRAL NERVOUS SYSTEM.	Abufène,Alanine, L-Isomer,L-Alanine,Alanine, L Isomer,L Alanine,L-Isomer Alanine
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D012997	Solvents	Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)	Solvent