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Allosteric regulation of an enzyme. In the fields of biochemistry and pharmacology an allosteric regulator (or allosteric modulator) is a substance that binds to a site on an enzyme or receptor distinct from the active site, resulting in a conformational change that alters the protein's activity, either enhancing or inhibiting its function.
The site to which the effector binds is termed the allosteric site. Allosteric sites allow effectors to bind to the protein, often resulting in a conformational change involving protein dynamics. Effectors that enhance the protein's activity are referred to as allosteric activators, whereas those that decrease the protein's activity are called ...
The site that an allosteric modulator binds to (i.e., an allosteric site) is not the same one to which an endogenous agonist of the receptor would bind (i.e., an orthosteric site). Modulators and agonists can both be called receptor ligands. [2] Allosteric modulators can be 1 of 3 types either: positive, negative or neutral.
However, in contrast to competitive and uncompetitive inhibitors, mixed inhibitors bind to the allosteric site. Allosteric binding induces conformational changes that may increase the protein's affinity for substrate. This phenomenon is called positive modulation. Conversely, allosteric binding that decreases the protein's affinity for ...
PFK1 is an allosteric enzyme and has a structure similar to that of hemoglobin in so far as it is a dimer of a dimer. [5] One half of each dimer contains the ATP binding site whereas the other half the substrate (fructose-6-phosphate or (F6P)) binding site as well as a separate allosteric binding site. [6]
The glycogen phosphorylase dimer has many regions of biological significance, including catalytic sites, glycogen binding sites, allosteric sites, and a reversibly phosphorylated serine residue. First, the catalytic sites are relatively buried, 15Å from the surface of the protein and from the subunit interface. [6]
It is important to note that while all non-competitive inhibitors bind the enzyme at allosteric sites (i.e. locations other than its active site)—not all inhibitors that bind at allosteric sites are non-competitive inhibitors. [1] In fact, allosteric inhibitors may act as competitive, non-competitive, or uncompetitive inhibitors. [1]
Allosteric Database (ASD) [1] provides a central resource for the display, search and analysis of the structure, function and related annotation for allosteric molecules. Currently, ASD contains allosteric proteins from more than 100 species and modulators in three categories (activators, inhibitors, and regulators).