A Histidine Was Determined to Be the Critical Residue Involved

question 81

Multiple Choice

A histidine was determined to be the critical residue involved in an enzyme-catalyzed reaction.If the pKa of the histidine is known to be 6.5 in the active site and the pH of maximum catalytic activity is 7.2,what is likely the primary role of histidine in the catalytic reaction?

• A)Acts as a proton donor or acceptor.
• B)Forms a covalent bond with the substrate.
• C)Stabilizes a charged intermediate.
• D)Reduces the entropy of the substrate.