I need help with biochemistry

Question

The covalent catalysis mechanism of an enzyme depends on a single active site Cys whose pKa is 8. A mutation in a nearby residue alters the microenvironment so that this pK increases to 10. Would the mutation cause the reaction rate increase or decrease?

Answer 1

The Cysteine amino acid's pKa of 8 has an established equilbrium which allows it to effectively participate in the active site. With the increase of pKa, this equilibrium has been altered and the reaction rate will decrease.