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Catalase is a tetramer of four polypeptide chains, each over 500 amino acids long. [7] It contains four iron-containing heme groups that allow the enzyme to react with hydrogen peroxide. The optimum pH for human catalase is approximately 7, [8] and has a fairly broad maximum: the rate of reaction does not change appreciably between pH 6.8 and 7 ...
In enzymology, the turnover number (k cat) is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration [E T] for enzymes with two or more active sites. [1] For enzymes with a single active site, k cat is referred to as the catalytic constant. [2]
An illustrative example is the effect of catalysts to speed the decomposition of hydrogen peroxide into water and oxygen: . 2 H 2 O 2 → 2 H 2 O + O 2. This reaction proceeds because the reaction products are more stable than the starting compound, but this decomposition is so slow that hydrogen peroxide solutions are commercially available.
Enzyme catalysis is the increase in the rate of a process by an "enzyme", a biological molecule. Most enzymes are proteins, and most such processes are chemical reactions. Within the enzyme, generally catalysis occurs at a localized site, called the active site.
Catalase-peroxidase (EC 1.11.1.21, katG ... This enzyme catalyses the following chemical reaction. ... This enzyme is a strong catalase with H 2 O 2 as donor which ...
[3] [4] Because this is such a large unit for most enzymatic reactions, the nanokatal (nkat) is used in practice. [4] = The katal is not used to express the rate of a reaction; that is expressed in units of concentration per second, as moles per liter per second. Rather, the katal is used to express catalytic activity, which is a property of ...
This is a two-electron oxidation/reduction reaction in which H 2 O 2 is reduced to water, and the enzyme is oxidized. One oxidizing equivalent resides on iron, giving the oxyferryl [ 1 ] intermediate, and in many peroxidases the porphyrin (R) is oxidized to the porphyrin pi-cation radical (R').
More so, the enzyme purifies as a consequence of crystallization, making cycles of crystallization an effective final purification step. Much like catalase, the reaction of cytochrome c peroxidase proceeds through a three-step process, forming first a Compound I and then a Compound II intermediate: CCP + ROOH → Compound I + ROH + H 2 O