Biomaterial Database

Differential effects of thiocyanate on the binding thermodynamics of bicuculline methiodide versus SR95531 (gabazine) to the gamma-aminobutyric acid receptor-ionophore complex. 1998

G Maksay

Central Research Institute for Chemistry, Hungarian Academy of Sciences, Budapest.

The temperature dependence of the binding of [3H]SR 95531 (Gabazine), an antagonist of gamma-aminobutyric acid (GABA(A)) receptors, was studied in synaptosomal membranes of rat brain in the presence of 50 mM KSCN. The displacing potencies of the antagonists bicuculline methiodide and Gabazine were determined at five temperatures between 0 degrees and 37 degrees. Van't Hoff plots of the displacing potencies were analyzed by linear regression in the presence and absence of thiocyanate. Thiocyanate hardly affected the exothermic ionic binding interaction of gabazine. In contrast, thiocyanate strongly potentiated the binding of bicuculline methiodide and deprived it of its exothermic nature. The enhanced binding of bicuculline methiodide in the presence of chaotropic SCN- ions might be reconciled with "entropic trapping" in a sterically constrained hydrophobic binding pocket.

UI	MeSH Term	Description	Entries
D007476	Ionophores	Chemical agents that increase the permeability of biological or artificial lipid membranes to specific ions. Most ionophores are relatively small organic molecules that act as mobile carriers within membranes or coalesce to form ion permeable channels across membranes. Many are antibiotics, and many act as uncoupling agents by short-circuiting the proton gradient across mitochondrial membranes.	Ionophore
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008297	Male		Males
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011724	Pyridazines	Six-membered rings with two adjacent nitrogen atoms also called 1,2-diazine.
D004396	Coloring Agents	Chemicals and substances that impart color including soluble dyes and insoluble pigments. They are used in INKS; PAINTS; and as INDICATORS AND REAGENTS.	Coloring Agent,Dye,Dyes,Organic Pigment,Stain,Stains,Tissue Stain,Tissue Stains,Organic Pigments,Pigments, Inorganic,Agent, Coloring,Inorganic Pigments,Pigment, Organic,Pigments, Organic,Stain, Tissue,Stains, Tissue
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001640	Bicuculline	An isoquinoline alkaloid obtained from Dicentra cucullaria and other plants. It is a competitive antagonist for GABA-A receptors.	6-(5,6,7,8-Tetrahydro-6-methyl-1,3-dioxolo(4,5-g)isoquinolin-5-yl)furo(3,4-e)1,3-benzodioxol-8(6H)one
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D013816	Thermodynamics	A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)	Thermodynamic