Section: Biological and Biochemical Foundations of Living Systems

1) An enzyme catalyst is kept in a solution buffered to the pH that maximizes activity for those enzymes found in the blood. The enzyme catalyzes a reaction that produces an acid whose pKa is 4.5. In this buffer solution, the acid product will be:

1. Primarily deprotonated
2. Primarily protonated
3. Protonated and deprotonated in roughly equal amounts
4. Not formed

The blood has a pH around 7.4, making it somewhat basic. If this enzyme is in a solution buffered to a point to maximize enzymes found in the blood, then the buffer solution will have a pH of 7.35 to 7.45. When an acid is in a solution whose pH is higher than its pKa, the acid is deprotonated, making choice (A) the correct answer. B: The acid would be protonated if the buffer solution had a pH that was below 4.5 C: The acid would have equal concentrations of the acid and conjugate base form if the buffer had a pH of around 4.5 D: There’s no reason for us to assume the product wouldn’t form.