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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 ...
Consider the reaction of peptide bond hydrolysis catalyzed by a pure protein α-chymotrypsin (an enzyme acting without a cofactor), which is a well-studied member of the serine proteases family, see. [40] We present the experimental results for this reaction as two chemical steps:
The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the non-catalyzed mechanism. However the non-catalyzed mechanism does remain possible, so that the total rate (catalyzed plus non-catalyzed) can only increase in the presence of the catalyst and never decrease. [5]
In contrast, the reaction of superoxide with SOD is first order with respect to superoxide concentration. Moreover, superoxide dismutase has the largest k cat /K M (an approximation of catalytic efficiency) of any known enzyme (~7 x 10 9 M −1 s −1), [24] this reaction being limited only by the frequency of collision between itself and ...
In 1972, it was observed that in the dehydration of H 2 CO 3 catalyzed by carbonic anhydrase, the second-order rate constant obtained experimentally was about 1.5 × 10 10 M −1 s −1, [5] which was one order of magnitude higher than the upper limit estimated by Alberty, Hammes, and Eigen based on a simplified model.
Catalase-peroxidase (EC 1.11.1.21, katG (gene)) ... This enzyme catalyses the following chemical reaction. donor + H 2 O 2 ⇌ oxidized donor + 2 H 2 O; 2 H 2 O 2 ⇌ ...
Catalase is an example of this, ... ENZO (Enzyme Kinetics) is a graphical interface tool for building kinetic models of enzyme catalyzed reactions. ENZO automatically ...
Activity of glutathione peroxidase is measured spectrophotometrically using several methods. A direct assay by linking the peroxidase reaction with glutathione reductase with measurement of the conversion of NADPH to NADP is widely used. [11] The other approach is measuring residual GSH in the reaction with Ellman's reagent.