0
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.
Wiki User
∙ 16y ago
Wiki User
∙ 11y agokm 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
Wiki User
∙ 7y agoIn 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.
Wiki User
∙ 15y agoenzyme activity is inversely proportional to the km value. ie higher the km value lower will be enzyme activity. suhail ahmed rahujo microbiologist
Wiki User
∙ 11y agoKm is constant and does not vary eith enzyme concentartion.because km denotes the affinity for a substrate towards an enzyme
Wiki User
∙ 9y agoAccording to scientists, the reason enzymes are important to metabolic reactions is that it aids in the acceleration of a reaction without changing the temperature.
Add your answer:
Earn +20 pts
What are k-series and v-series enzymes?
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
Suppose that the enzyme concentration was increased by a factor of four what would be the value of km and vmax?
KM would not change, since it is a constant. Vmax would half, because Vmax depends on the concentration of the enzyme.
How do you determine Vmax in enzyme kinetics?
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.
High enzyme kcat means low Km?
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.
What is the effect of competitive inhibitor of an enzyme on lineweaver-burke plot?
Vmax (y-intercept) remains the same and the Km (x-intercept) changes
True or False Low Km means that an enzyme binds very loosely to a substrate andd consequently results in a high velocity compared to an enzyme with a high Km?
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.
What is the type of enzyme inhibition in which the Km changes but the Vmax does not?
competitive
What are k-series and v-series enzymes?
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
Does vmax increase with increasing amount of enzyme?
Yes, Vmax has a linear relationship with the amount of enzyme. This in turn deceases the Km of the reaction.
Suppose that the enzyme concentration was increased by a factor of four what would be the value of km and vmax?
KM would not change, since it is a constant. Vmax would half, because Vmax depends on the concentration of the enzyme.
The initial rate of an enzyme catalysed reaction depend on?
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.
How do you determine Vmax in enzyme kinetics?
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.
What happens to the vmax when a competitive reversible inhibitor is added to an enzyme?
The vmax stays the same as the competitive reversible inhibitor does not affect catalysis in the enzyme-substrate.
High enzyme kcat means low Km?
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.
What is the effect of competitive inhibitor of an enzyme on lineweaver-burke plot?
Vmax (y-intercept) remains the same and the Km (x-intercept) changes
What does increased Vmax suggest?
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.
What is michelis menten curve how it is useful in the study of enzyme kinetics?
The michaelis menten cruve is a plot of initial velocity vs substrate concentration. From this plot one can measure a Vmax and Km.
