Ch 8.2 Lecture
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Why did enzyme kinetics come about?
for people who study enzymes, you need to mathematically model them
Explain how they study the enzymes.
- They put 1 mL buffer in a cuvette
- They add enzymes (a ton of enzymes)
- They add substrate
Shake it up--> spec to assay
Explain the assay from doing this.
over time, you get different substrate concentrations due to enzymes reacting differently.It results in a graph with a number of different concentrations
What is the presteady state?
It is the beginning of teh reactions when all of the components of the experiment are put in together. It is the very beginning of the process, when it is just starting. It happens too quickly to be able to study
What is the part we want to view when studying enzymes?
It is the V0 . And, it appears to be linear
What happens to the concentrations of E and ES
Free [E] is going to decrease because E is being used to form the complex.
The concentration of ES is going to increase because more ES complex is forming
What is the steady state?
the change in the concentration of ES overtime is 0
the part of the curve where ES is forming at the same time/ amount as ES is breaking down
What does the pre-steady state look like in terms of graphs?
initially, it is slow, then it gets linear and levels off
What is the common graph for single substrate, nonallosteric enzymes?
The graph of V0 being almost parabolic and leveling off right before reaching Vmax.
For a given [S], V0 increases. But it increases to a point where it nears Vmax but never gets there
What are the definitions for Km?
- Michaelis-Menten constant
- equal to the breakdown rates over the formation rates
What is Michaelis-Menten Kinetics?
a mathematical model that attempts to describe the curve of enzyme activity with an equation.
What is V0?
What is the equation?
how much [ES] do we have; and, how much is going forward
Rate of formation of [ES]
Rate of breakdown of [ES]
** set equal to each other**
What will the concentration of [ES] be equal to?
Km is (k2+k-1)/k1
What is Vmax?
the fastest the reaction can go
How to connect Km and Vmax.
V0=Vmax ( [S]/([S] + Km)
Vmax= k2 [Et] (all enzymes are reacting at the forward rate)
Does the MM Kinetics correctly describe the curve?
Yes. The reason for this is because at the beginning of the curve, it seems to increase in a linear fashion. As you get to the point that equals the KM, the reaction velocity will equal exactly half of the Vmax. When the substrate concentration continues to increase at a super high rate, we'll never reach the Vmax but we will get very close
What would you like to do?
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