The Michaelis constant (Km) is a means of characterising an enzyme's affinity for a substrate. The Km in an enzymatic reaction is the substrate concentration at which the reaction rate is half its maximum speed.
Thus, a low Km value means that the enzyme has a high affinity for the substrate (as a "little" substrate is enough to run the reaction at half its max speed).
This is only true for reactions where substrate is limiting and the enzyme is NOT allosteric.
km is the molar concentration of the substrate at which half of maximum velocity is attained.Here some significance of km is as follows-
1.The affinity of e4nzyme substrate interaction determine by the km of the enzyme
2.km is irreversibly proportional with the substrate affinity. when km rises the substrate affinity decreases and when km decreases the substrate affinity increases
In Enzymology, KM is referred to the Michaelis Constant. This constant has a simple operational definition, considering the Michaelis-Menten equation (in honor to Leonor Michaelis and Maud Menten, two of the principal "parents" of enzymology): vo = Vmax [S] / KM + [S], where vo is the initial velocity of the reaction, Vmax is the maximal velocity, [S] is the substrate concentration, and KM the Michaelis Constant.
The Michaelis Constant is explained as: at the substrate concentration where [S] = KM, yields vo (the initial velocity of the reaction) = Vmax / 2 so that KM is the substrate concentration at which the reaction velocity is half-maximal. Therefore, if an enzyme has a small value of KM, it achieves maximal catalytic eficiency at low substrate concentration. The magnitud of KM vareis widely with the identity of the enzyme and the nature of the substrate. Furthermore, is a function of temperature and pH.
The Michaelis constant can be expressed as: KM = k-1 / k1 + k2 / k1 = Ks + k2 / k1 (where, k-1 is the enzyme-substrate complex disociation constant into enzyme and substrate, k1 is the enzyme-substrate complex asociation constant, and k2 is the enzyme-substrate complex disociation constant to form product and the enzyme). Since Ks is the dissociation constant of the Michaelis complex, as Ks decreases, the enzyme's affinity for substrate increases. KM is therefore also a measure of the affinity of the enzyme for its substrate providing k2 / k1 is small compared with Ks, that is, k2 < k-1.
enzyme activity is inversely proportional to the km value. ie higher the km value lower will be enzyme activity. suhail ahmed rahujo microbiologist
Km is constant and does not vary eith enzyme concentartion.because km denotes the affinity for a substrate towards an enzyme
According to scientists, the reason enzymes are important to metabolic reactions is that it aids in the acceleration of a reaction without changing the temperature.
A K-Series enzyme is an enzyme that changes the Km of an enzyme on the michaelis menten or lineweaver burk graphs A V-series enzyme affects the Vmax
KM would not change, since it is a constant. Vmax would half, because Vmax depends on the concentration of the enzyme.
Vmax is the maxim initial velocity (Vo) that an enzyme can achieve. Initial velocity is defined as the catalytic rate when substrate concentration is high, enough to saturate the enzyme, and the product concentration is low enough to neglect the rate of the reverse reaction. Therefore, the Vmax is the maximum catalytic rate that can be achieved by a particular enzyme. Km is determined as the substrate concentration at which 1/2 Vmax is achieved. This kinetic parameter therefore importantly defines the affinity of the substrate for the enzyme. These two parameters for a specific enzyme defines: Vmax - the rate at which a substrate will be converted to product once bound to the enzyme. Km - how effectively the enzyme would bind he substrate, hence affinity.
Not necessarily. You could have a relatively high Kcat but a moderate Km value. This is of course relative to all enzymes across the board. An example would be to compare catalase and acetylcholinesterase. Catalase has a Km of 1.1M but a Kcat of 4 X 10*7 while acetylcholinesterase has a Km of 9 X 10*-5 but a Kcat value of only 1.4 X 10*4. While a low Km value will definitely mean a high affinity of enzyme for substrate, this does not readily eqaute to a high Kcat value.
Vmax (y-intercept) remains the same and the Km (x-intercept) changes
False. A high Km means that an enzyme binds very loosely to a substrate and consequently results in a high velocity compared to an enzyme with a high Km.
competitive
A K-Series enzyme is an enzyme that changes the Km of an enzyme on the michaelis menten or lineweaver burk graphs A V-series enzyme affects the Vmax
Yes, Vmax has a linear relationship with the amount of enzyme. This in turn deceases the Km of the reaction.
KM would not change, since it is a constant. Vmax would half, because Vmax depends on the concentration of the enzyme.
Based on Michaelis-Menten enzyme kinetics, the initial rate of reaction, vi, is dependent on maximum rate Vmax, substrate concentration [S], and the enzyme's Michaelis constant Km, which represents the the tendency of the substrate/enzyme complex to dissociate. The dependence on enzyme concentration is factored into the maximum rate. The equation to describe this is: vi = Vmax([S]/(Km+[S])) Follow the link below for details.
Vmax is the maxim initial velocity (Vo) that an enzyme can achieve. Initial velocity is defined as the catalytic rate when substrate concentration is high, enough to saturate the enzyme, and the product concentration is low enough to neglect the rate of the reverse reaction. Therefore, the Vmax is the maximum catalytic rate that can be achieved by a particular enzyme. Km is determined as the substrate concentration at which 1/2 Vmax is achieved. This kinetic parameter therefore importantly defines the affinity of the substrate for the enzyme. These two parameters for a specific enzyme defines: Vmax - the rate at which a substrate will be converted to product once bound to the enzyme. Km - how effectively the enzyme would bind he substrate, hence affinity.
The vmax stays the same as the competitive reversible inhibitor does not affect catalysis in the enzyme-substrate.
Not necessarily. You could have a relatively high Kcat but a moderate Km value. This is of course relative to all enzymes across the board. An example would be to compare catalase and acetylcholinesterase. Catalase has a Km of 1.1M but a Kcat of 4 X 10*7 while acetylcholinesterase has a Km of 9 X 10*-5 but a Kcat value of only 1.4 X 10*4. While a low Km value will definitely mean a high affinity of enzyme for substrate, this does not readily eqaute to a high Kcat value.
Vmax (y-intercept) remains the same and the Km (x-intercept) changes
An increase in Vmax suggest an increase in the amount of enzyme in the reaction. Also this increase in Vmax deceases the Km vaule, which means less substrate is needed.
The michaelis menten cruve is a plot of initial velocity vs substrate concentration. From this plot one can measure a Vmax and Km.