Unit 3: Topic 3 - Environmental Impacts on Enzyme Function Flashcards
What does it mean when a protein is denatured, and how does it affect its function?
A protein is said to be denatured when the protein structure is disrupted or when its secondary or tertiary structures are disrupted. This results in a change in the protein’s shape, which would negatively affect an enzyme’s ability to catalyze a chemical reaction since the shape of the active site of a protein is what determines if the substrate will bind onto the enzyme, allowing the reaction to occur.
How do environmental temperatures and pH levels affect an enzyme’s ability to catalyze reactions?
A given enzyme has an optimal range for temperatures and pH levels in which the enzyme works the best and catalyzes chemical reactions fastest. When the environmental temperature and/or pH level is outside the optimal range, then the enzyme’s efficiency decreases. The further away the environmental conditions are from the optimal range, the lower the enzyme’s efficiency. In extreme cases, the enzyme can denature.
Is enzyme denaturation reversible?
In many cases, the denaturation of an enzyme is reversible, given that the denaturing agent is removed. In these cases, the enzyme can resume its function. In extreme cases, however, such as frying an egg, denaturation is not reversible, and the enzyme’s function is lost forever. Protein denaturation is said to be irreversible when the denatured state is unable to return to the biologically functional state upon removal of the denaturing agent.
In terms of intermolecular bonds, how do changes in environmental pH affect the efficiency of enzyme activity?
Alterations in the concentration of H+ (pH) in the solution surrounding the protein can disrupt the hydrogen bonds that provide the enzyme structure. It can also change the patterns of ionization of the exposed carboxyl and amino groups, which can disrupt the patterns of ionic attractions and repulsions
How do the relative concentrations of substrates affect how efficiently an enzymatic reaction occurs?
The higher the concentration of substrate, the more efficiently an enzymatic reaction occurs. As the concentration of substrates decreases, the reactions will slow and soon cease.
How do the relative concentrations of products affect how efficiently an enzymatic reaction occurs?
In some cases, the products combine with the active site of the enzyme and form a loose complex and, thus, inhibit the enzyme activity, which means that as the concentration of products increases, the efficiency of the enzymatic reaction decreases.
How do the relative concentrations of enzymes affect how efficiently an enzymatic reaction occurs?
The higher the concentration of enzymes, the more efficiently the enzymatic reaction occurs. The higher the concentration of enzymes, the more enzymes there are to catalyze the reaction, thus increasing the reaction rate.
How does environmental temperature affect the efficiency of an enzymatic reaction?
The higher the environmental temperature, assuming it does not denature the protein, the greater the speed of movement of molecules in a solution, increasing the frequency of collisions between enzymes and substrates and, therefore, increasing the rate of reaction. The lower the environmental temperature, the slower the speed of molecular movement in a solution, thus decreasing the rate of reaction.
What are competitive inhibitors, and how do they affect the efficiency of an enzymatic reaction?
Competitive inhibitors are molecules that are similar enough to a particular enzyme’s natural substrate that they can bind noncovalently to the active site, yet different enough that no chemical reaction occurs. In this way, it competes with the natural substrate for the active site, thus decreasing the efficiency of the enzyme. Competitive inhibition is reversible. When the concentration of the competitive inhibitor is reduced, the active site is less likely to be occupied by the inhibitor, and the enzyme regains activity.
What are noncompetitive inhibitors, and how do they affect the efficiency of an enzymatic reaction?
Noncompetitive inhibitors, also known as allosteric inhibitors, bind to an enzyme at a site distinct from the active site. This binding causes a change in the shape (the conformation) of the enzyme, altering its activity. The active site may no longer bind the substrate, or if it does, the rate of product formation may be reduced. Like competitive inhibitors, noncompetitive inhibitors can become unbound, so their effects are reversible.
