Home > Quantitative Structure-Activity Relationship
QSAR (Quantitative Structure-Activity Relationship, sometimes the A stands also for Affinity= reactivity) is the quantitative correlation of the biological ( ecological, toxicological or pharmacological) activity to the structure of chemical compounds, which allows the prediction of the so-called " drug efficacy " of a structurally related compound. It is thus closely related to the more general field of QSPR and employs many of the latter's methodology.The biological activity of molecules is usually measured in assays to establish the level of inhibition of particular signal transduction or metabolic pathways. Chemicals can also be biologically active by being toxic. Drug discovery often involves the use of QSAR to identify chemical structures that could have good inhibitory effects on specific targets and have low toxicity (non-specific activity). Of special interest is the prediction of LogPLogP is a measure of differential solubility of a compound in two solvents. The log ratio of the concentrations of the solute in the solvent is called LogP or the Partition Coefficient . The most well known of these partition coefficients is the one based, which is an important measure used in in identifying " drug-likeness " according to Lipinski's Rule of FiveChristopher A. Lipinski formulated a so-called rule of 5 as criteria for oral bioavailability. See ADME) These four "rules" are common characteristics found in most drugs available today. The rule of 5 derives its name from the fact that the relevant cuto.
While many the determination of Quantitative Structure Activity Relationships involve analysing the interactions of a family of molecules with an enzymeAn enzyme is a protein, or protein complex, that catalyzes a chemical reaction. Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed to its steady state or completion much faster than it ot or receptorIn biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm that binds to a specific factor (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. As all receptors binding site, QSAR can also be used to study the interactions between the structural domainWithin a protein, a structural domain ("domain") is an element of overall structure that is self-stabilizing and often folds independently of the rest of the protein chain. Many domains are not unique to the protein products of one gene or one gene familys of proteins. As in the article Structural modeling extends QSAR analysis of antibody-lysozyme interactions to 3D-QSAR, protein-protein interactions can be quantitatively analyzed for structural variations resukted from site-directed mutagenesisin vitro mutagenesis) Site-directed mutagenesis is a molecular biology technique in which a mutation is created at a defined site in a DNA molecule. In general, site-directed mutagenesis requires that the wild-type gene sequence be known. An oligonucleoti. In this study, a wild-type antibodyantigen An antibody is a protein complex used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target. Antibody structure Antibodies are glycoproteins foun specific for lysozyme and 17 single and double mutants of the antibody were investigated. Quantitative models for the affinity of the antibody- antigen interaction were developed.
3D-QSAR is a specialization concerned with three-dimensional quantitative structure-activity relationships . This involves the analysis of the three-dimensional properties of molecules ( chemical conformation).
Note: QSAR is often pronounced as "Quasar", but it is not related to Quasars in astronomy.
