Table of Contents
How does low substrate concentration affect enzyme activity?
(A) At low concentration of substrate, there is a steep increase in the rate of reaction with increasing substrate concentration. The rate of formation of product now depends on the activity of the enzyme itself, and adding more substrate will not affect the rate of the reaction to any significant effect.
What effect does substrate concentration have on enzyme activity?
Enzymes will work best if there is plenty of substrate. As the concentration of the substrate increases, so does the rate of enzyme activity. However, the rate of enzyme activity does not increase forever.
How does concentration of enzyme affect enzyme activity?
Enzyme concentration: Increasing enzyme concentration will speed up the reaction, as long as there is substrate available to bind to. Once all of the substrate is bound, the reaction will no longer speed up, since there will be nothing for additional enzymes to bind to.
What does a lower substrate concentration mean?
If substrate concentration is low, enzymes have a lower chance of encountering the substrate, so its activity, or rate of reaction, is low. The rate of an enzyme reaction is the amount of substrate converted to product over a period of time.
What is the problem in determining rates at low substrate concentration?
For low substrate concentrations (relative to the Km), depletion of the substrate causes the reaction to slow down more than at higher substrate concentration, so a low enzyme concentration is needed to maintain the initial rate long enough for the initial rate measurement to be made.
What is the effect of substrate concentration on the rate of activity?
Hydrogen peroxide is also a dangerous, very potent by-product of metabolism, and it is essential that it is broken down quickly so it does not cause damage to cells. Investigate the effect of substrate concentration on the rate of activity of the enzyme catalase.
How is the concentration of a substrate related to the affinity of an enzyme?
This is usually expressed as the Km (Michaelis constant) of the enzyme, an inverse measure of affinity. For practical purposes, Km is the concentration of substrate which permits the enzyme to achieve half Vmax. An enzyme with a high Km has a low affinity for its substrate, and requires a greater concentration of substrate to achieve Vmax.”
What happens when an enzyme is saturated with a substrate?
The rate of reaction when the enzyme is saturated with substrate is the maximum rate of reaction, Vmax. The relationship between rate of reaction and concentration of substrate depends on the affinity of the enzyme for its substrate.
How are the km and Vmax of an enzyme determined?
Km and Vmax are determined by incubating the enzyme with varying concentrations of substrate; the results can be plotted as a graph of rate of reaction (v) against concentration of substrate ([S], and will normally yield a hyperbolic curve, as shown in the graphs above.