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Flashcards in Enzyme Kinetics Deck (28):

What does Delta H mean?.

Delta H means H formation of products -H formation of reactants


What does Delta A mean?

Delta S means the change in entropy. Positive Delta S means more entropy in products than reactants.


What is delta G?

Delta G is Gibbs Free Energy. It is calculated by the formula
Delta G=Delta H-T (Delta S)


What are the X axis and Y axis of a reaction coordinate graph?

The X axis is the energy in the system, the Y axis is the reaction coordinate (definition not very clear, but symbolizes progression of reaction)


What is the difference between the first point and the last point on a reaction-coordinate graph?

It is the Delta G


What is the point where Activation Energy is on the reaction coordinate graph?

Activation energy is on the topmost point of the reaction coordinate graph.


What is T(delta S) equal to?

It is equal to kinetic energy.


At what G value is the Delta G equal to zero?

At Zero,


What does it mean of the reaction if it has a Negative Delta G?

It means that reaction is EXERGONIC, and is spontaneous


What does it mean if a reaction has a positive Delta G?

It means that the positive Delta G means the reaction is endergonic and non-spontaneous.


What is the role of a catalyst in a reaction?
How do catalysts achieve this goal?

It increases the rate at which a reaction reaches equilibrium by
1) Lowering the Ea
2) By stabilizing Transition State


What is the number one way to regulate enzyme activity?
Does this activate the enzyme, deactivate the enzyme, or both?

1) Phosphorylation
It does not have a specific inhibiting or activating role, it can go either way.


What is another way to regulate an enzyme?

Allosteric regulation: Allosteric regulation is when a regulator binds to another are on the enzyme to regulate it


What is negative feedback?

Negative feedback is when the product of a particlar reaction inhibits the enxyme that facilitates the first step of that reaction or reaction in general


What is positive feedback? Is it a regulation method?

It is the opposite of negative feedback, and no, it is not a regulator, but instead is a step used to reach a certain endpoint.


How does a positive feedback loop end?

Via an external regulator. For example, in the nervous system, positive regulation creates an action potential, which then resets the system. Positive feedback loop acts like the external regulator. In labor, the pushing out baby "resets" the system and causes the contraction to oxytocin release feedback loop to end.


Describe V vs S graphs

V vs S graphs:
Y axis is V (Velocity)
X axis is S (Substrate concentration)


What do V vs S graphs reveal?

Vmax for a particular enzyme at a particular concentration,

Km, which is the particular affinity of an enzyme.


What is the relationship between Km and enzyme affinity?

Inverse. Kn is the amount of Substrate needed to reach half of Vmax, so more substrate needed= less affinity.


What are the effects of a competitive inhibitor on the V vs S graph?

Vmax will be same,

Km will be increased.


What is non-competitive inhibition?

Non-competitive inhibition is when an inhibitor binds to an allosteric site of an unbound enzyme


What are the effects of non-competitive inhibition?

Vmax will decrease,
Km will be the same


What is uncompetitive inhibition?

when an inhibitor binds to an enzyme- substrate complex.


What are the effects of uncompetitive inhibition on V vs S graph?

The effects would be that both Vmax and Km will decrease


What is mixed inhibition?

an inhibitor that can bind to the enzyme alone or enzyme substrate complex allsterically.


What is effect of mixed inhibitor on V vs S graph?

V max decreases, while the effects on Km will vary.


How are Lineweaver Burke Plot and V vs. S graphs related?

Line weaver burker blots are the inverse of V vs S plots.


How do you read a Lineweaver-Burke Plot?

You read a Lineweaver Burke Plot by knowing that the closer the value is to zero, the "larger it is"