Question

Michaelis-Menten kinetics define the way in which enzymes behave at various substrate concentrations. Unlike the linear reaction rates discussed in organic chemistry, enzymes can only turn over substrate at a rate that is equal to or less than the amount of time it takes to bind to the enzyme, therefore, at high enough substrate concentrations, there will be no effect on the reaction rate. This is termed reaching Vmax, or the maximum velocity the enzyme can turn over product. From the Vmax, we are able to determine the KM of the reaction, which is a constant based on various enzyme substrate interactions.

Instructions: On the graph below, please label both Vmax and KM based on the information provided to you. Use lines to indicate where the Km falls in comparison to ½ Vmax

Answer 1

Ans. Determining Km and Vmax using MM plot:

I. Extrapolate Vmax on Y-axis (line A). Vmax = 44 uM/ min (approx..)

II. Calculate half of Vmax. ½ Vmax = ½ (44.0 mM/min) = 22.0 uM/min

III. Extrapolate ½ Vmax value on Y-axis to the hyperbola curve.

It is shown as line B.

IV. Extrapolate the y-intersection on curve down to the X-axis. It is shown as line C. The intersection on X-axis gives the value of Km. Km = 3.0 Mm.