Chapter 2 Flashcards
What are the 7 key features of an enzyme?
- Lower Activation Energy
- Increase reaction rate
- Does not alter equilibrium constant
- Not consumed in reaction
- PH and temperature sensitive
- Does not effect delta G
- Is specific for a reaction
What are the 6 classes of enzyme?
- Ligase
- Isomerase
- Lyase
- Hydrolase
- Oxioreductase
- Transferase
What is ligase?
Ligase is an enzyme that catalayses building things via using ATP.
What is Isomerase?
Isomerase catalyzes the rearrangement of bonds. It can be considered transferase, etc..
What is Lyase
Lyase cleaves a single molecule into two products without addition of water or transfer of electrons
What is hydrolase
An enzyme that breaks a compound into 2 using water
What is an oxioreductase
An enzyme that catalyzes oxidation reduction
What is transferase
an enzyme that catalyzes movement of a functional group from one molecule to another
What is an endorgonic reaction
A reaciton that has a positive delta g and needs energy input
How do enzymes lower the activation energy of a reaction?
Enzymes lower the activation energy of a reaction by stabilizing the transition state. This is usually accomplished by the enzyme’s structure which will create a microenviroment that is favorable to the transition state and stabilizes it. (hydrogen bonds, ionic interactions to modify local charge environment, electron donor or acceptor, transient covalent bonds)
What is an active site
where the enzyme holds the substrate while it catalyzes the reaction
Describe the induced fit theory of enzyme activity?
The induced fit theory states that an enzyme is usually in a relaxed form, and that the binding of the substrate to the enzyme causes the enzyme to change its shape and accomodate the substrate. This initally requires energy so ES complex goes DOWN in free enrgy initially (but not enough to have a worse activation energy)
What is a cofactor or coenzyme?
A cofactor or coenzyme is any nonprotein molecule that is required for the enzyme to function properly. usually carries charge in enzyme reaction through ionization, protonation or deprotonation. tend to be small in size and are in low, tightly regulated concentrations within cells.
What is an apoenzyme?
An apoenzyme is an enzyme without its cofactor.
What is a holoenzyme?
A holoenzyme is an enzyme with its necessary cofactor.
What is the difference between a coenzyme and a prosthetic group?
A prosthetic group is just coenzyme that is very tightly bound to the enzyme (can be covalent) and is critical for its function.
What is saturation?
Saturation is the point at which every enzyme has a substrate bound. Adding substrate at this point will not increase the speed of the reaction.
What is vmax?
Vmax is the theoretical maximum velocity at which the reaction can run based on the number of enzymes present. This is the velocity at which every single enzyme is bound to a substrate molecule.
What is the only way to increase vmax?
Adding more enzymes for substrate molecules to bind to.
What is Km
Km (AKA the Michaelis Constant) is the concentration at which half of the enzyme’s active sites are in use and the velocity of the reaction is half of the Vmax.
Km can be used to compare the affinities of different enzymes for specific substrates. For example, an enzyme with a Km of .5M needs .5M of substrate to occupy half of its active sites. However, an enzyme with a Km of .25M only needs .25M of substrate to occupy half of its active sites.
