Question

only 7-9,11-12

7. When does the KM equal the Kd? 8. The kcat refers to which steps in the catalytic mechanism? 9. The KM refers to which steps in the catalytic mechanism? L0. Calculate the Km, when v = .123 HM/sec, [E]T = 1.0 HM, kcat 720/s and [S 11. Which constant would you use to compare substrate specificities? 12. The upper limit of enzyme catalysis is called...?

Answer 1

Solution:

7) Kd = k1 / k-1

and

Km = k2 + k1 / k-1

When, k2 <<<< k1

Then, Km reduces to k1 / k2 = Kd

8) kcat is the turn over number. It indicates the rate at which enzyme turns over, it means kcat = k2 and measures the number of substrate molecules turned over by substrate molecules. Thus used in second step.

9)When, Km = [S] then V= Vmax / 2

Thus, used in first step in catalytic reaction mechanism.

11) Km (Mechalis constant) is used to compare substrate specificities.

12) The upper limit of enzyme catalysis is called saturation point.