Enzyme Kinetics Flashcards
What is a catalyst?
A catalyst is a molecule that increases the rate in a chemical reaction without themselves being changed in the process.
Enzymes lower the ___________ of a reaction.
Activation energy
The _________ of an enzyme is where catalysis takes place.
Active Site
Bound metal ions can help __________ or can be a powerful driving force in ____________
position the substrate; oxidation-reduction reactions
In general acid-base chemistry, the amino acid side chain of an enzyme can donate or accept _________ to stabilize transitions states.
Protons
When cofactors or coenzymes are tightly bound to an enzyme, it is called a ____________
Prosthetic group
The velocity of a given enzymatic reaction depends on __________
The amount of substrate
Km is the amount of substrate needed for the enzyme velocity to be at __________
1/2Vmax
Kcat is the number of substrate molecules converted to product in a given unit time for a given enzyme molecule when ____________
The enzyme is saturated with substrate
The __________ the number from the ratio of Kcat/Km, the closer to enzymatic perfection
Larger
What are the three types of reversible inhibitors?
- Competitive 2. Uncompetitive 3. Mixed
A competitive inhibitor binds only to the ________ and not to the _________ and competes with the substrate for the __________
Enzyme, enzyme-substrate complex, active site
A competitive inhibitor _________ Km.
Increases
An uncompetitive inhibitor binds to the enzyme in a place other than the __________ and only to the _________
Active site; enzyme-substrate complex
Uncompetative inhibitors ________ Vmax
decreases
Mixed inhibitor binds outside the ________ but can bind to either the ________ or __________
Active site, Enzyme; Enzyme-Substrate complex
Penicillin is an example of an ____________
Irreversible inhibitor
Allosteric regulation of an enzyme
Binding of another molecule changes the conformation of the enzyme and alters function; usually involves feedback loops
Covalent modification of an enzyme
Involves phosphorylation and is in response to intra/extra cellular signals
Proteolytic cleavage on an enzyme
Once an enzyme is cleaved into a smaller segment, it is activated
What are the four types of enzymatic regulators?
Allosteric, Covalent, Binding of another regulatory protein, Proteolytic cleavage
