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The Lineweaver–Burk plot derives from a transformation of the Michaelis–Menten equation, = + in which the rate is a function of the substrate concentration and two parameters , the limiting rate, and , the Michaelis constant.
Determining the parameters of the Michaelis–Menten equation typically involves running a series of enzyme assays at varying substrate concentrations , and measuring the initial reaction rates , i.e. the reaction rates are measured after a time period short enough for it to be assumed that the enzyme-substrate complex has formed, but that the ...
Synthesizing units (SUs) are generalized enzymes that follow the rules of classic enzyme kinetics with two modifications: . product formation is not taken to be a function of substrate concentrations but of substrate fluxes that arrive at the SUs
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.
The amount of substrate needed to achieve a given rate of reaction is also important. This is given by the Michaelis–Menten constant (K m), which is the substrate concentration required for an enzyme to reach one-half its maximum reaction rate; generally, each enzyme has a characteristic K M for a given substrate.
Substrate inhibition in bioreactors occurs when the concentration of substrate (such as glucose, salts, or phenols [1]) exceeds the optimal parameters and reduces the growth rate of the cells within the bioreactor. This is often confused with substrate limitation, which describes environments in which cell growth is limited due to of low substrate.
The substrate concentration midway between these two limiting cases is denoted by K M. Thus, K M is the substrate concentration at which the reaction velocity is half of the maximum velocity. [2] The two important properties of enzyme kinetics are how easily the enzyme can be saturated with a substrate, and the maximum rate it can achieve.
The enzyme unit, or international unit for enzyme (symbol U, sometimes also IU) is a unit of enzyme's catalytic activity. [ 1 ] 1 U (μmol/min) is defined as the amount of the enzyme that catalyzes the conversion of one micro mole of substrate per minute under the specified conditions of the assay method .