Topic #4: Enzyme Kinetics Calculation
Recommended problems in Campbell, Chapter 5: #21, 22, 24.
Model reaction: E + S <=>
(ES<->EP) --> E + P
- The Michaelis-Menten equation is:
vo = Vmax[S]/(KM
+ [S]) , where
- vo = the initial velocity;
- Vmax = the maximal velocity;
- [S] = the substrate concentration;
- KM = [S] at half-maximal velocity,
i.e.the Michaelis constant.
We want to determine Vmax and KM by measuring
the dependence of the initial velocity on the substrate concentration.
This is done in three steps.
(Each calculated vo value has a small "experimental
error" added to it.
Tabbing out of the [A] entry slot or clicking anywhere on the page
will also calculate vo.)
3. Record the values of [S] and vo you obtain; then
graph them on a double reciprocal plot to determine KM
and Vmax. You should get enough data so as to have
3 or 4 values of vo, both above and below the KM
value.
(Hint: Graph the values you obtain as they are calculated;
then as the shape of the curve becomes apparent, choose values
for [S] that fall into the appropriate range.)
Answers to this problem.
A sample Answer Sheet
for a similar problem shows the format of the results and the
graph required.
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