A metallic element of atomic number 30 and atomic weight 65.38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with ANEMIA, short stature, HYPOGONADISM, impaired WOUND HEALING, and geophagia. It is known by the symbol Zn.

Motifs in DNA- and RNA-binding proteins whose amino acids are folded into a single structural unit around a zinc atom. In the classic zinc finger, one zinc atom is bound to two cysteines and two histidines. In between the cysteines and histidines are 12 residues which form a DNA binding fingertip. By variations in the composition of the sequences in the fingertip and the number and spacing of tandem repeats of the motif, zinc fingers can form a large number of different sequence specific binding sites.

A compound given in the treatment of conditions associated with zinc deficiency such as acrodermatitis enteropathica. Externally, zinc sulfate is used as an astringent in lotions and eye drops. (Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Englewood, CO, 1995)

Inorganic compounds that contain zinc as an integral part of the molecule.

A salt produced by the reaction of zinc oxide with acetic acid and used as an astringent, styptic, and emetic.

A mild astringent and topical protectant with some antiseptic action. It is also used in bandages, pastes, ointments, dental cements, and as a sunblock.

Stable zinc atoms that have the same atomic number as the element zinc, but differ in atomic weight. Zn-66-68, and 70 are stable zinc isotopes.

Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.

Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.

The parts of a macromolecule that directly participate in its specific combination with another molecule.

The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.

An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.

Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

A low-molecular-weight (approx. 10 kD) protein occurring in the cytoplasm of kidney cortex and liver. It is rich in cysteinyl residues and contains no aromatic amino acids. Metallothionein shows high affinity for bivalent heavy metals.

The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed)

Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.

A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.

Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.

A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.

An element with atomic symbol Cd, atomic number 48, and atomic weight 114. It is a metal and ingestion will lead to CADMIUM POISONING.

Activated form of factor XII. In the initial event in the intrinsic pathway of blood coagulation, kallikrein (with cofactor HIGH MOLECULAR WEIGHT KININOGEN) cleaves factor XII to XIIa. Factor XIIa is then further cleaved by kallikrein, plasmin, and trypsin to yield smaller factor XII fragments (Hageman-Factor fragments). These fragments increase the activity of prekallikrein to kallikrein but decrease the procoagulant activity of factor XII.

Ethylenediamines are organic compounds containing two amine groups linked by a two-carbon chain, widely used in the manufacture of industrial and pharmaceutical products, including chelating agents and polymerization catalysts, but not typically used as a medication on their own.

The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.

The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).

The rate dynamics in chemical or physical systems.

The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.

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.

A chelating agent that has been used to mobilize toxic metals from the tissues of humans and experimental animals. It is the main metabolite of DISULFIRAM.

An essential amino acid that is required for the production of HISTAMINE.

Electrodes which can be used to measure the concentration of particular ions in cells, tissues, or solutions.

The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

A chelating agent that sequesters a variety of polyvalent cations such as CALCIUM. It is used in pharmaceutical manufacturing and as a food additive.

Proteins that have one or more tightly bound metal ions forming part of their structure. (Dorland, 28th ed)

The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.

Positively-charged atomic nuclei that have been stripped of their electrons. These particles have one or more units of electric charge and a mass exceeding that of the Helium-4 nucleus (alpha particle).

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.

A species of gram-negative, facultatively anaerobic, rod-shaped bacteria that may be pathogenic for frogs, fish, and mammals, including man. In humans, cellulitis and diarrhea can result from infection with this organism.

Stable blood coagulation factor activated by contact with the subendothelial surface of an injured vessel. Along with prekallikrein, it serves as the contact factor that initiates the intrinsic pathway of blood coagulation. Kallikrein activates factor XII to XIIa. Deficiency of factor XII, also called the Hageman trait, leads to increased incidence of thromboembolic disease. Mutations in the gene for factor XII that appear to increase factor XII amidolytic activity are associated with HEREDITARY ANGIOEDEMA TYPE III.

The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.

A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.

A strain of ENCEPHALOMYOCARDITIS VIRUS, a species of CARDIOVIRUS, isolated from rodents and lagomorphs and occasionally causing febrile illness in man.

The region of an enzyme that interacts with its substrate to cause the enzymatic reaction.

A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.

Poisoning occurring after exposure to cadmium compounds or fumes. It may cause gastrointestinal syndromes, anemia, or pneumonitis.

The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.

The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.

The protein components of enzyme complexes (HOLOENZYMES). An apoenzyme is the holoenzyme minus any cofactors (ENZYME COFACTORS) or prosthetic groups required for the enzymatic function.

A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.

A plasma protein which is the precursor of kallikrein. Plasma that is deficient in prekallikrein has been found to be abnormal in thromboplastin formation, kinin generation, evolution of a permeability globulin, and plasmin formation. The absence of prekallikrein in plasma leads to Fletcher factor deficiency, a congenital disease.

A cadmium halide in the form of colorless crystals, soluble in water, methanol, and ethanol. It is used in photography, in dyeing, and calico printing, and as a solution to precipitate sulfides. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)

Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.

An enzyme that activates leucine with its specific transfer RNA. EC 6.1.1.4.

A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)

A zinc-containing enzyme which oxidizes primary and secondary alcohols or hemiacetals in the presence of NAD. In alcoholic fermentation, it catalyzes the final step of reducing an aldehyde to an alcohol in the presence of NADH and hydrogen.

A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.

Carboxypeptidases that are primarily found the DIGESTIVE SYSTEM that catalyze the release of C-terminal amino acids. Carboxypeptidases A have little or no activity for hydrolysis of C-terminal ASPARTIC ACID; GLUTAMIC ACID; ARGININE; LYSINE; or PROLINE. This enzyme requires ZINC as a cofactor and was formerly listed as EC 3.4.2.1 and EC 3.4.12.2.

A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.

Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.

Endogenous peptides present in most body fluids. Certain enzymes convert them to active KININS which are involved in inflammation, blood clotting, complement reactions, etc. Kininogens belong to the cystatin superfamily. They are cysteine proteinase inhibitors. HIGH-MOLECULAR-WEIGHT KININOGEN; (HMWK); is split by plasma kallikrein to produce BRADYKININ. LOW-MOLECULAR-WEIGHT KININOGEN; (LMWK); is split by tissue kallikrein to produce KALLIDIN.

The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.

The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.

A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.

GLYCOSPHINGOLIPIDS with a sulfate group esterified to one of the sugar groups.

A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.

ENDOPEPTIDASES which use a metal such as ZINC in the catalytic mechanism.

Proteins prepared by recombinant DNA technology.

Proteins found in any species of bacterium.

The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.

A group of chemical elements that are needed in minute quantities for the proper growth, development, and physiology of an organism. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.

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.

Phenanthrolines are a class of heterocyclic compounds containing two aromatic hydrocarbon rings fused with a third ring consisting of nitrogen atoms, which have been used in the development of various pharmaceutical and chemical research applications, including as antibacterial, antifungal, and antiviral agents, enzyme inhibitors, and chelators.

Solution titration in which the end point is read from the electrode-potential variations with the concentrations of potential determining ions. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The process by which two molecules of the same chemical composition form a condensation product or polymer.

A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

A transfer RNA which is specific for carrying leucine to sites on the ribosomes in preparation for protein synthesis.

Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.

The relationship between the dose of an administered drug and the response of the organism to the drug.

Membrane proteins whose primary function is to facilitate the transport of positively charged molecules (cations) across a biological membrane.

The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.

Chloride and mercury-containing derivatives of benzoic acid.

A thermostable extracellular metalloendopeptidase containing four calcium ions. (Enzyme Nomenclature, 1992) 3.4.24.27.

The characteristic 3-dimensional shape and arrangement of multimeric proteins (aggregates of more than one polypeptide chain).

Elements of limited time intervals, contributing to particular results or situations.

A mass-spectrometric technique that is used for microscopic chemical analysis. A beam of primary ions with an energy of 5-20 kiloelectronvolts (keV) bombards a small spot on the surface of the sample under ultra-high vacuum conditions. Positive and negative secondary ions sputtered from the surface are analyzed in a mass spectrometer in regards to their mass-to-charge ratio. Digital imaging can be generated from the secondary ion beams and their intensity can be measured. Ionic images can be correlated with images from light or other microscopy providing useful tools in the study of molecular and drug actions.

The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)

A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)

A general class of integral membrane proteins that transport ions across a membrane against an electrochemical gradient.

Reversible chemical reaction between a solid, often one of the ION EXCHANGE RESINS, and a fluid whereby ions may be exchanged from one substance to another. This technique is used in water purification, in research, and in industry.

Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.

A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).

A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).

Large, hoofed mammals of the family EQUIDAE. Horses are active day and night with most of the day spent seeking and consuming food. Feeding peaks occur in the early morning and late afternoon, and there are several daily periods of rest.

Amidohydrolases are enzymes that catalyze the hydrolysis of amides and related compounds, playing a crucial role in various biological processes including the breakdown and synthesis of bioactive molecules.

The protein components of a number of complexes, such as enzymes (APOENZYMES), ferritin (APOFERRITINS), or lipoproteins (APOLIPOPROTEINS).

Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.

Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.

The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.

A class of compounds that reduces the secretion of H+ ions by the proximal kidney tubule through inhibition of CARBONIC ANHYDRASES.

A subclass of EXOPEPTIDASES that act on the free N terminus end of a polypeptide liberating a single amino acid residue. EC 3.4.11.

Chemical groups containing the covalent sulfur bonds -S-. The sulfur atom can be bound to inorganic or organic moieties.

A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Established cell cultures that have the potential to propagate indefinitely.

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)

Proteolytic enzymes from the serine endopeptidase family found in normal blood and urine. Specifically, Kallikreins are potent vasodilators and hypotensives and increase vascular permeability and affect smooth muscle. They act as infertility agents in men. Three forms are recognized, PLASMA KALLIKREIN (EC 3.4.21.34), TISSUE KALLIKREIN (EC 3.4.21.35), and PROSTATE-SPECIFIC ANTIGEN (EC 3.4.21.77).

Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.

Enzymes that act at a free C-terminus of a polypeptide to liberate a single amino acid residue.

Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).

Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.

A subclass of enzymes which includes all dehydrogenases acting on primary and secondary alcohols as well as hemiacetals. They are further classified according to the acceptor which can be NAD+ or NADP+ (subclass 1.1.1), cytochrome (1.1.2), oxygen (1.1.3), quinone (1.1.5), or another acceptor (1.1.99).

Spectrophotometric techniques by which the absorption or emmision spectra of radiation from atoms are produced and analyzed.

The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.

Measurement of the intensity and quality of fluorescence.

The process of cleaving a chemical compound by the addition of a molecule of water.

An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.

A reagent commonly used in biochemical studies as a protective agent to prevent the oxidation of SH (thiol) groups and for reducing disulphides to dithiols.

Compounds containing the -SH radical.

Transport proteins that carry specific substances in the blood or across cell membranes.

Complexing agent for removal of traces of heavy metal ions. It acts also as a hypocalcemic agent.

The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat.

A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.

Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.

A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry.

Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.

A non-essential amino acid naturally occurring in the L-form. Glutamic acid is the most common excitatory neurotransmitter in the CENTRAL NERVOUS SYSTEM.

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.

Products in capsule, tablet or liquid form that provide dietary ingredients, and that are intended to be taken by mouth to increase the intake of nutrients. Dietary supplements can include macronutrients, such as proteins, carbohydrates, and fats; and/or MICRONUTRIENTS, such as VITAMINS; MINERALS; and PHYTOCHEMICALS.

Compounds based on fumaric acid.

Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

Peptides composed of two amino acid units.

The dose amount of poisonous or toxic substance or dose of ionizing radiation required to kill 50% of the tested population.

An enzyme that catalyzes the conversion of an orthophosphoric monoester and water to an alcohol and orthophosphate. EC 3.1.3.1.

Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein.

The molecular designing of drugs for specific purposes (such as DNA-binding, enzyme inhibition, anti-cancer efficacy, etc.) based on knowledge of molecular properties such as activity of functional groups, molecular geometry, and electronic structure, and also on information cataloged on analogous molecules. Drug design is generally computer-assisted molecular modeling and does not include pharmacokinetics, dosage analysis, or drug administration analysis.

Metals with high specific gravity, typically larger than 5. They have complex spectra, form colored salts and double salts, have a low electrode potential, are mainly amphoteric, yield weak bases and weak acids, and are oxidizing or reducing agents (From Grant & Hackh's Chemical Dictionary, 5th ed)

The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.

The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.

Uptake of substances through the lining of the INTESTINES.

Regular course of eating and drinking adopted by a person or animal.

A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.

The sum of the weight of all the atoms in a molecule.

The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).

Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.

Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.

Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.

An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.

Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.

A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.

A filament-like structure consisting of a shaft which projects to the surface of the SKIN from a root which is softer than the shaft and lodges in the cavity of a HAIR FOLLICLE. It is found on most surfaces of the body.

Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES).

A subclass of ion channels that open or close in response to the binding of specific LIGANDS.

Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.

A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.

Separation technique in which the stationary phase consists of ion exchange resins. The resins contain loosely held small ions that easily exchange places with other small ions of like charge present in solutions washed over the resins.

Derivatives of SUCCINIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a 1,4-carboxy terminated aliphatic structure.

Proteins obtained from ESCHERICHIA COLI.

Materials which have structured components with at least one dimension in the range of 1 to 100 nanometers. These include NANOCOMPOSITES; NANOPARTICLES; NANOTUBES; and NANOWIRES.

State of the body in relation to the consumption and utilization of nutrients.

The use of a heavy ion particle beam for radiotherapy, such as the HEAVY IONS of CARBON.

An essential branched-chain amino acid important for hemoglobin formation.

The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.

Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.

The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.

High molecular weight, insoluble polymers which contain functional groups that are capable of undergoing exchange reactions (ION EXCHANGE) with either cations or anions.

Proteins found in any species of virus.

The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)

Positively charged atoms, radicals or group of atoms with a valence of plus 1, which travel to the cathode or negative pole during electrolysis.

Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.

The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.

The ability of a substrate to allow the passage of ELECTRONS.

The processes whereby the internal environment of an organism tends to remain balanced and stable.

The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action.

Used as a dental cement this is mainly zinc oxide (with strengtheners and accelerators) and eugenol. (Boucher's Clinical Dental Terminology, 4th ed, p50)

The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.

Any food that has been supplemented with essential nutrients either in quantities that are greater than those present normally, or which are not present in the food normally. Fortified food includes also food to which various nutrients have been added to compensate for those removed by refinement or processing. (From Segen, Dictionary of Modern Medicine, 1992)

Essential dietary elements or organic compounds that are required in only small quantities for normal physiologic processes to occur.

The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.

A class of compounds of the type R-M, where a C atom is joined directly to any other element except H, C, N, O, F, Cl, Br, I, or At. (Grant & Hackh's Chemical Dictionary, 5th ed)

An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.

Metals that constitute group 1(formerly group Ia) of the periodic table. They are the most strongly electropositive of the metals. Note that HYDROGEN is not considered an alkali metal even though it falls under the group 1 heading in the periodic table.

A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.

Inorganic or organic compounds that contain divalent iron.

Native, inorganic or fossilized organic substances having a definite chemical composition and formed by inorganic reactions. They may occur as individual crystals or may be disseminated in some other mineral or rock. (Grant & Hackh's Chemical Dictionary, 5th ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.

A mass spectrometry technique using two (MS/MS) or more mass analyzers. With two in tandem, the precursor ions are mass-selected by a first mass analyzer, and focused into a collision region where they are then fragmented into product ions which are then characterized by a second mass analyzer. A variety of techniques are used to separate the compounds, ionize them, and introduce them to the first mass analyzer. For example, for in GC-MS/MS, GAS CHROMATOGRAPHY-MASS SPECTROMETRY is involved in separating relatively small compounds by GAS CHROMATOGRAPHY prior to injecting them into an ionization chamber for the mass selection.

The amounts of various substances in food needed by an organism to sustain healthy life.

Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.

The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.

Conditions characterized by an alteration in gustatory function or perception. Taste disorders are frequently associated with OLFACTION DISORDERS. Additional potential etiologies include METABOLIC DISEASES; DRUG TOXICITY; and taste pathway disorders (e.g., TASTE BUD diseases; FACIAL NERVE DISEASES; GLOSSOPHARYNGEAL NERVE DISEASES; and BRAIN STEM diseases).

An element in the alkali metals family. It has the atomic symbol Li, atomic number 3, and atomic weight [6.938; 6.997]. Salts of lithium are used in treating BIPOLAR DISORDER.

Gluconates are salts or esters of gluconic acid, primarily used in medical treatments as a source of the essential nutrient, calcium, and as a chelating agent to bind and remove toxic metals such as aluminum and iron from the body.

The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.

Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.