Question

DI LUS his tell you about the T U SHIP Between substrate) and enzymes with high KM values? With low Km values? Make a generalization. Occurs when we know [s] must be equal to KM, Km refers to binding affinity of enzyme 10 Substrate - higher km- tow binding affinity - WoW Km= high binding Affinity [5]= 1.5.6 = 1.75 5. a. What is the Ky value as you can estimate it from Graph 1? S pe =AY-1.75 -0_1.17 13.61 Vmax = 4.2 AX 1.5-0 b. On Graph 1, draw a curve that has the same Vmax but a smaller Kvalue. 1. 6. Examine Equation 2. When k, is very small compared to k., the KM becomes an approximation of the affinity of enzymes for substrate. Explain why this approximation makes sense. Does a large Kvindicate high or low affinity of enzyme for substrate?

Answer 1

Question 5.

KM = (k-1 + k2)/k1, i.e. Higher the Km, the smaller is the binding affinity. Lower the KM, the greater it is.

The slope of the Line-weaver Burk plot = KM/Vmax, KM = slope * Vmax = 1.17 * 4.2 = 4.9 mM

Question 6.

If K-1 >> k2, then KM = k-1/k1 = 1/K, i.e. the reciprocal of the equilibrium constant for the binding of E to S.

Large KM indicates a low affinity of the enzyme for the substrate.