Question

Protein 1 has KD = 0.09 mM for glucose, while Protein 2 has KD = 0.06 mM. What does this mean?

a) Protein 2 binds substrate more tightly than Protein 1
b) Protein 1 binds substrate more tightly than Protein 2
c) Protein 2 has more binding sites than Protein 1
d) Protein 1 has more binding sites than Protein 2

Answer 1

Protein 2, with a KD of 0.06 mM, binds glucose more tightly than Protein 1 with a KD of 0.09 mM, indicating a higher affinity. The correct answer is a) Protein 2 binds substrate more tightly than Protein 1.

Step-by-step explanation:

Regarding the given protein's affinity for glucose, the KD (dissociation constant) is inversely related to affinity. A lower KD value indicates a higher affinity because it means that the protein will be half-saturated at a lower concentration of glucose. Therefore, Protein 2 with a KD of 0.06 mM will bind more tightly to glucose compared to Protein 1 with a KD of 0.09 mM.

The correct answer to the student's question is a) Protein 2 binds substrate more tightly than Protein 1. This interpretation is directly related to the binding affinity of the proteins for glucose and does not necessarily indicate anything about the number of binding sites.