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The rate of reaction of many chemical reactions shows a linear response as function of the concentration of substrate molecules. Enzymes however display a saturation effect where,, as the substrate concentration is increased the reaction rate reaches a maximum value. Standard approaches to describing this behavior are based on models developed ...
Biochemical reactions involving a single substrate are often assumed to follow Michaelis–Menten kinetics, without regard to the model's underlying assumptions. Only a small proportion of enzyme-catalysed reactions have just one substrate, but the equation still often applies if only one substrate concentration is varied.
For a given enzyme concentration and for relatively low substrate concentrations, the reaction rate increases linearly with substrate concentration; the enzyme molecules are largely free to catalyse the reaction, and increasing substrate concentration means an increasing rate at which the enzyme and substrate molecules encounter one another.
In biochemistry, control coefficients [1] are used to describe how much influence a given reaction step has on the flux or concentration of the species at steady state.This can be accomplished experimentally by changing the expression level of a given enzyme and measuring the resulting changes in flux and metabolite levels.
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.
Enzyme activity. An enzyme's name is often derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase. [1]: 8.1.3 Examples are lactase, alcohol dehydrogenase and DNA polymerase. Different enzymes that catalyze the same chemical reaction are called isozymes. [1]: 10.3
The rate of a reaction is the concentration of substrate disappearing (or product produced) per unit time (mol L −1 s −1). The % purity is 100% × (specific activity of enzyme sample / specific activity of pure enzyme). The impure sample has lower specific activity because some of the mass is not actually enzyme.
Regulatory enzymes are commonly the first enzyme in a multienzyme system: the product of the reaction catalyzed by the first enzyme is the substrate of the second enzyme, so the cell can control the amount of resulting product by regulating the activity of the first enzyme of the pathway.