Question

a) For most enzymes, the K_m is closely related to the affinity of the enzyme for its substrate(s). Which has higher affinity, an enzyme with a low K_m, or an enzyme with a high K_m? Justify your answer.

b) True or false: at a pH equal to its pKA, the average charge on an ionizable amino acid sidechain (such as lysine's ε-amino group) will be zero.

c) Titration of isoleucine by a strong base, for example NaOH, reveals two pK’s. The titration reaction occurring at pK1 (pK1 = 2.4) is:

A) —COOH + OH⁻→ —COO⁻+ H₂O.

B) —COOH + —NH₂→ —COO⁻+ —NH₂.

C) —COO⁻+ —NH₂→ —COOH + —NH₂.

D) —NH₃⁺+ OH⁻→ —NH₂+ H₂O.

E) —NH₂+ OH⁻→ —NH− + H₂O.

Circle the correct answer.

Answer 1