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Organisation of enzyme structure and lysozyme example. Binding sites in blue, catalytic site in red and peptidoglycan substrate in black. (In biology and biochemistry, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction.
Binding site in blue, inhibitor in green, and substrate in black. In the scope of cancer, ligands that are edited to have a similar appearance to the natural ligand are used to inhibit tumor growth. For example, Methotrexate, a chemotherapeutic, acts as a competitive inhibitor at the dihydrofolate reductase active site. [40]
In biochemistry, a zymogen (/ ˈ z aɪ m ə dʒ ən,-m oʊ-/ [1] [2]), also called a proenzyme (/ ˌ p r oʊ ˈ ɛ n z aɪ m / [3] [4]), is an inactive precursor of an enzyme.A zymogen requires a biochemical change (such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the active site) for it to become an active enzyme.
The active site is a region on an enzyme to which a particular protein or substrate can bind. The active site will thus only allow one of the two complexes to bind to the site, either allowing a reaction to occur or yielding it. In competitive inhibition, the inhibitor resembles the substrate, taking its place and binding to the active site of ...
The active site is located at a cleft between the two β-barrel domains, in which functionally important residues are contributed from each domain. Genetically engineered mutants of the chymotrypsin serine protease were shown to have some proteinase activity even though their active site residues were abolished and it has therefore been ...
The sophistication of the active site network causes residues involved in catalysis (and residues in contact with these) to be highly evolutionarily conserved. [62] However, many examples of divergent evolution in catalytic triads exist, both in the reaction catalysed, and the residues used in catalysis.
Enzymes that use a metal in the active site are called "metallo-carboxypeptidases" (EC number 3.4.17). Other carboxypeptidases that use active site serine residues are called "serine carboxypeptidases" (EC number 3.4.16). Those that use an active site cysteine are called "cysteine carboxypeptidase" (or "thiol carboxypeptidases")(EC number 3.4.18).
For example, a drug that treats high blood pressure, Captopril, was designed based on a carboxypeptidase A inhibitor. Carboxypeptidase A and the target enzyme of Captopril, angiotensin-converting enzyme, have very similar structures, as they both contain a zinc ion within the active site.