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Biological Target
A biological target is anything within a living organism to which some other entity (like an endogenous ligand or a drug) is directed and/or binds, resulting in a change in its behavior or function. Examples of common classes of biological targets are proteins and nucleic acids. The definition is context-dependent, and can refer to the biological target of a pharmacologically active drug compound, the receptor target of a hormone (like insulin), or some other target of an external stimulus. Biological targets are most commonly proteins such as enzymes, ion channels, and receptors. Mechanism The external stimulus (''i.e.'', the drug or ligand) physically binds to ("hits") the biological target. The interaction between the substance and the target may be: * noncovalent – A relatively weak interaction between the stimulus and the target where no chemical bond is formed between the two interacting partners and hence the interaction is completely reversible. * reversible covalent â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand (biochemistry)
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a molecule which produces a signal by binding to a site on a target protein. The binding typically results in a change of conformational isomerism (conformation) of the target protein. In DNA-ligand binding studies, the ligand can be a small molecule, ion, or protein which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure. Binding occurs by intermolecular forces, such as ionic bonds, hydrogen bonds and Van der Waals forces. The association or docking is actually reversible through dissociation. Measurably irreversible covalent bonding between a ligand and target molecule is atypical in biological systems. In contrast to the definition of lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Structure
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers specifically polypeptides formed from sequences of amino acids, the monomers of the polymer. A single amino acid monomer may also be called a ''residue'' indicating a repeating unit of a polymer. Proteins form by amino acids undergoing condensation reactions, in which the amino acids lose one water molecule per reaction in order to attach to one another with a peptide bond. By convention, a chain under 30 amino acids is often identified as a peptide, rather than a protein. To be able to perform their biological function, proteins fold into one or more specific spatial conformations driven by a number of non-covalent interactions such as hydrogen bonding, ionic interactions, Van der Waals forces, and hydrophobic packing. To understand the functions of proteins at a molecular level, it is often necessary to determine their three-dimensional structure. This is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage-gated Ion Channel
Voltage-gated ion channels are a class of transmembrane proteins that form ion channels that are activated by changes in the electrical membrane potential near the channel. The membrane potential alters the conformation of the channel proteins, regulating their opening and closing. Cell membranes are generally impermeable to ions, thus they must diffuse through the membrane through transmembrane protein channels. They have a crucial role in excitable cells such as neuronal and muscle tissues, allowing a rapid and co-ordinated depolarization in response to triggering voltage change. Found along the axon and at the synapse, voltage-gated ion channels directionally propagate electrical signals. Voltage-gated ion-channels are usually ion-specific, and channels specific to sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl−) ions have been identified. The opening and closing of the channels are triggered by changing ion concentration, and hence charge gradient, between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand-gated Ion Channel
Ligand-gated ion channels (LICs, LGIC), also commonly referred to as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as Na+, K+, Ca2+, and/or Cl− to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter. When a presynaptic neuron is excited, it releases a neurotransmitter from vesicles into the synaptic cleft. The neurotransmitter then binds to receptors located on the postsynaptic neuron. If these receptors are ligand-gated ion channels, a resulting conformational change opens the ion channels, which leads to a flow of ions across the cell membrane. This, in turn, results in either a depolarization, for an excitatory receptor response, or a hyperpolarization, for an inhibitory response. These receptor proteins are typically composed of at least two different domains: a transmembrane domain which includes the ion pore, and an extracellular domain wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatase
In biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acid Ester, monoester into a phosphate ion and an Alcohol (chemistry), alcohol. Because a phosphatase enzyme catalysis, catalyzes the hydrolysis of its Substrate (chemistry), substrate, it is a subcategory of hydrolases. Phosphatase enzymes are essential to many biological functions, because phosphorylation (e.g. by protein kinases) and dephosphorylation (by phosphatases) serve diverse roles in cell growth, cellular regulation and cell signaling, signaling. Whereas phosphatases remove phosphate groups from molecules, kinases catalyze the transfer of phosphate groups to molecules from Adenosine triphosphate, ATP. Together, kinases and phosphatases direct a form of post-translational modification that is essential to the cell's regulatory network. Phosphatase enzymes are not to be confused with phosphorylase enzymes, which catalyze the transfer of a phosphate group from hydrogen phosphate to an acce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Esterase
An esterase is a hydrolase enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis. A wide range of different esterases exist that differ in their substrate specificity, their protein structure, and their biological function. EC classification/list of enzymes * ''EC 3.1.1'': Carboxylic ester hydrolases ** Acetylesterase (EC 3.1.1.6), splits off acetyl groups *** Cholinesterase **** Acetylcholinesterase, inactivates the neurotransmitter acetylcholine **** Pseudocholinesterase, broad substrate specificity, found in the blood plasma and in the liver ** Pectinesterase (EC 3.1.1.11), clarifies fruit juices * ''EC 3.1.2'': Thiolester hydrolases ** Thioesterase *** Ubiquitin carboxy-terminal hydrolase L1 * ''EC 3.1.3'': Phosphoric monoester hydrolases ** Phosphatase (EC 3.1.3.x), hydrolyses phosphoric acid monoesters into a phosphate ion and an alcohol *** Alkaline phosphatase, removes phosphate groups from many types of molecules, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protease
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in many biological functions, including digestion of ingested proteins, protein catabolism (breakdown of old proteins), and cell signaling. In the absence of functional accelerants, proteolysis would be very slow, taking hundreds of years. Proteases can be found in all forms of life and viruses. They have independently evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms. Hierarchy of proteases Based on catalytic residue Proteases can be classified into seven broad groups: * Serine protease ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Kinase
A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a functional change of the target protein ( substrate) by changing enzyme activity, cellular location, or association with other proteins. The human genome contains about 500 protein kinase genes and they constitute about 2% of all human genes. There are two main types of protein kinase. The great majority are serine/threonine kinases, which phosphorylate the hydroxyl groups of serines and threonines in their targets and most of the others are tyrosine kinases, although additional types exist. Protein kinases are also found in bacteria and plants. Up to 30% of all human proteins may be modified by kinase activity, and kinases are known to regulate the majority of cellular pathways, especially those involved in signal transduction. Chemical ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G Protein-coupled Receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. Coupling with G proteins, they are called seven-transmembrane receptors because they pass through the cell membrane seven times. Text was copied from this source, which is available under Attribution 2.5 Generic (CC BY 2.5) license. Ligands can bind either to extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (Rhodopsin-like family). They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed. G protein-coupled receptors are found only in eukaryotes, including yeast, choanoflagellates, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adverse Effect
An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term complication is similar to adverse effect, but the latter is typically used in pharmacological contexts, or when the negative effect is expected or common. If the negative effect results from an unsuitable or incorrect dosage or procedure, this is called a medical error and not an adverse effect. Adverse effects are sometimes referred to as "iatrogenic" because they are generated by a physician/treatment. Some adverse effects occur only when starting, increasing or discontinuing a treatment. Adverse effects can also be caused by placebo treatments (in which case the adverse effects are referred to as nocebo effects). Using a drug or other medical intervention which is contraindicated may increase the risk of adverse effects. Adverse effects may c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Therapeutic Effect
Therapeutic effect refers to the response(s) after a treatment of any kind, the results of which are judged to be useful or favorable. This is true whether the result was expected, unexpected, or even an unintended consequence. An adverse effect (including nocebo) is the converse and refers to harmful or undesired response(s). What constitutes a therapeutic effect versus a side effect is a matter of both the nature of the situation and the goals of treatment. No inherent difference separates therapeutic and undesired side effects; both responses are behavioral/physiologic changes that occur as a response to the treatment strategy or agent. Treatment scope To maximize therapeutic effects (desired) and minimize side effects (undesired) requires recognition and quantification of the treatment in multiple dimensions. In the specific case of targeted pharmaceutical interventions, a combination of therapies is often needed to achieve the desired results. Pharmacology examples *A 201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pharmaceutical
A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and relies on the science of pharmacology for continual advancement and on pharmacy for appropriate management. Drugs are classified in multiple ways. One of the key divisions is by level of control, which distinguishes prescription drugs (those that a pharmacist dispenses only on the order of a physician, physician assistant, or qualified nurse) from over-the-counter drugs (those that consumers can order for themselves). Another key distinction is between traditional small molecule drugs, usually derived from chemical synthesis, and biopharmaceuticals, which include recombinant proteins, vaccines, blood products used therapeutically (such as IVIG), gene therapy, monoclonal antibodies and cell therapy (for instance, stem cell therapies) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
