Factors affecting Enzyme Activity | A Level Notes
The higher the substrate concentration the faster the reaction is. This is becuase there are more substrate molecules so a collision between. Changing these alter the rate of reaction caused by the enzyme. In a fluid, this means that there are more random collisions between molecules per unit time. concentrations affect the rate of reaction of an enzyme-catalysed reaction. These suggest that the relationship between Enzyme concentration and rate of reaction is directly proportional. The graph of rate of enzyme concentration and.
However, a few enzymes have optimum pH values outside this range. For example, the optimum pH for pepsin, an enzyme that is active in the stomach, is 2. Summary Initially, an increase in substrate concentration leads to an increase in the rate of an enzyme-catalyzed reaction.
As the enzyme molecules become saturated with substrate, this increase in reaction rate levels off.
The rate of an enzyme-catalyzed reaction increases with an increase in the concentration of an enzyme. At low temperatures, an increase in temperature increases the rate of an enzyme-catalyzed reaction.
At higher temperatures, the protein is denatured, and the rate of the reaction dramatically decreases. An enzyme has an optimum pH range in which it exhibits maximum activity.
Enzyme Concentration (Introduction to Enzymes)
Concept Review Exercises The concentration of substrate X is low. What happens to the rate of the enzyme-catalyzed reaction if the concentration of X is doubled? What effect does an increase in the enzyme concentration have on the rate of an enzyme-catalyzed reaction? Answers If the concentration of the substrate is low, increasing its concentration will increase the rate of the reaction. An increase in the amount of enzyme will increase the rate of the reaction provided sufficient substrate is present.
Exercises In non-enzyme-catalyzed reactions, the reaction rate increases as the concentration of reactant is increased. In an enzyme-catalyzed reaction, the reaction rate initially increases as the substrate concentration is increased but then begins to level off, so that the increase in reaction rate becomes less and less as the substrate concentration increases. If an enzyme is to be used to determine the concentration of substrate in a sample e.
18.7: Enzyme Activity
The relationship is defined by the Michaelis-Menten equation: A number of ways of re-arranging the Michaelis-Menten equation have been devised to obtain linear relationships which permit more precise fitting to the experimental points, and estimation of the values of Km and Vmax. There are advantages and disadvantages associated with all three main methods of linearising the data. The Lineweaver-Burk double reciprocal plot rearranges the Michaelis-Menten equation as: These are the points at which the precision of determining the rate of reaction is lowest, because the smallest amount of product has been formed.
The Eadie-Hofstee plot rearranges the Michaelis-Menten equation as: However, it has the disadvantage that v, which is a dependent variable, is used on both axes, and hence errors in measuring the rate of reaction are multiplied, resulting in lower precision of the estimates of Km and Vmax The Hanes plot rearranges the Michaelis-Menten equation as: However, it has the disadvantage that [S] is used on both axes, and hence pipetting errors, which lead to errors in the true concentration of substrate available, are multiplied, resulting in lower precision of the estimates of Km and Vmax.
When the enzyme concentration is small, Vmax is much smaller. The reaction rate still increases with increasing substrate concentration, but levels off at a much lower rate.
By increasing the enzyme concentration, the maximum reaction rate greatly increases. The rate of a chemical reaction increases as the substrate concentration increases.
Enzymes can greatly speed up the rate of a reaction.
However, enzymes become saturated when the substrate concentration is high. Additionally, the reaction rate depends on properties of the enzyme K, kcat and the enzyme concentration E. Graph this function and interpret the graph.