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. |