Final answer:
Single amino acid substitutions in enzymes can lead to a range of outcomes, from no effect to total loss of function, depending on the importance of the altered residue. Some substitutions may also alter enzyme properties such as optimal temperature and pH. Dramatic changes like reverse reaction catalysis or altered substrate specificity are less common.
Step-by-step explanation:
Mutations that result in single amino acid substitutions in an enzyme can have a range of effects. These effects depend on the specific role that the altered amino acid plays within the protein. For instance, a single amino acid change may:
- Do not affect the activity or properties of the enzyme if the substituted amino acid does not play a critical role in enzyme function.
- Destroy the activity of the enzyme if the change occurs at a crucial site for its catalytic function, stability, or substrate binding.
- Impact the physicochemical properties of the enzyme, such as its optimal temperature and pH, especially if the mutated residue contributes to the structure of the active site.
However, a single amino acid substitution is less likely to:
- Result in the enzyme running reactions in reverse, as this requires significant changes in the enzyme's structure and mechanism.
- Change the enzyme's substrate specificity unless the specificity-determining residues are affected.
In some cases, such as with sickle cell disease, a single substitution can cause severe structural changes, leading to diseases. In other cases, the change can be more subtle, potentially altering enzyme efficiency without completely preventing its function.