Free Energy Flashcards
If Delta G increases what happens to the rate of the reaction? What about decreases? How do enzymes catalyze reactions?
delta G increases -> reaction gets slower
delta G decreases -> reaction gets faster
They decrease delta G
What are enzymes? Name some general properties
Molecules that accelerate biochemical reactions without being altered themselves. Have several general properties:
- Specificity: specific for a particular type of reaction
- Active site: Specialized location where the substrate binds
- Substrate binding
What is the V of the reaction at any given substrate concentration?
V= Vmax ([S]/[Km+[S])
Also remember Km=[S] and V= Vmax/2
An enzyme with a small Km indicates that the reaction can reach half it’s maximum velocity at [ X ] concentrations. This enzyme has a [ X ] affinity for the substrate.
Do the reverse for large Km
- low, high
2. high, low
What are competitive inhibitors? How are they overcome? What does it do to Vmax and Km?
Molecules that look like the substrate and bind to the active site.
In order to overcome must increase the substrate concentration
Increases the Km of the enzyme but does not change the Vmax
What are non-competitive inhibitors? How are they overcome? What does it do to Vmax and Km?
Molecule that binds to a site on the enzyme that IS NOT the active site.
Unclear how to overcome. The substrate can bind to the enzyme with equal affinity, but it can’t convert the substrate to product as efficiently as when the non-competitive inhibitor is not bound.
It reduces Vmax and does not change Km
How do you quantify the effectiveness of an inhibitor for a specific enzyme by KI?
KI is the measure of affinity of the inhibitor for a specific enzyme
Competitive: When the concentration of the inhibitor equals the KI, then it takes twice as much substrate to reach a velocity of Vmax/2
Non-competitive: When the concentration of the inhibitor equals the K1, then the velocity of the reaction is decreased by a factor of two at every substrate concentration.
When is a reaction spontaneous reaction (delta G)? Does it depend on the pathway? Does it give information about the rate of the reaction?
It is spontaneous if it is negative. It is independent of the pathway that is followed to convert the reactants to the final products. It does not tell anything about the rate of the reaction, only if it will move in the direction predicted by change in G.
