L1 Enzymes Flashcards
Lyases is a type of enzyme that catalyze which type of reaction?
Group elimination to form double bonds
Ligases is a type of enzyme that catalyze which type of reaction?
Bond formation coupled with ATP hydrolysis
Lactate dehydrogenase is an example of which type of enzyme?
A. Oxidoreductases
B. Transferases
C. Hydrolases
D. Lyases
E. Isomerases
F. Ligases
Oxidoreductases
Alanine transaminase is an example of which type of enzyme?
A. Oxidoreductases
B. Transferases
C. Hydrolases
D. Lyases
E. Isomerases
F. Ligases
Transferases
Pyrophosphatase is an example of which type of enzyme?
A. Oxidoreductases
B. Transferases
C. Hydrolases
D. Lyases
E. Isomerases
F. Ligases
Hydrolases
Pyruvate decarboxylase is an example of which type of enzyme?
A. Oxidoreductases
B. Transferases
C. Hydrolases
D. Lyases
E. Isomerases
F. Ligases
Lyases
Alanine racemase is an example of which type of enzyme?
A. Oxidoreductases
B. Transferases
C. Hydrolases
D. Lyases
E. Isomerases
F. Ligases
Isomerases
Glutamine synthetase is an example of which type of enzyme?
A. Oxidoreductases
B. Transferases
C. Hydrolases
D. Lyases
E. Isomerases
F. Ligases
Ligases
Competitive inhibition can be overcome by what?
(1) Increasing substrate concentration
(2) Increasing reaction time
* Could not be overcame by increasing reaction temperature
What are the three essential assumptions for driving the M-M equation?
(1) Early in the reaction (close to time zero), there is no ES formation from E + P because [P] is negligible, hence k-2 can be ignored
(2) Steady state assumption for enzyme-substrate complex concentration [ES]
(3) Maximum reaction velocity (Vmax) occurs when enzyme is saturated with substrate
Among Km, Vmax and Kcat, which can be determined experimentally and how?
Km and Vmax, by measuring of initial velocities at a series of substrate concentrations and a fixed enzyme concentration
How to calculate Kcat?
kcat = Vmax /[E]total
Irreversible inhibitor binds to the enzyme through covalent bonds or non-covalent bond?
Covalent bonds
A type of inhibitor raises Km without effecting Vmax, what type of inhibitor is it?
Competitive inhibitor
What does the competitive inhibitor bind to?
Free enzyme
What does the uncompetitive inhibitor bind to?
ES complex
A type of inhibitor lowers both Km and Vmax, what type of inhibitor is it?
Uncompetitive inhibitor
Does the uncompetitive inhibitor raise the enzyme affinity or lower it? Why?
Raise it.
As it binds to the ES complex, the amount of ES complex is reduced. As a result, formation of ES from E + S will be enhanced. This means binding of S to E is enhanced, therefore Km is lowered, and the enzyme affinity is raised.
What does the noncompetitive inhibitor bind to?
E or ES complex
A type of inhibitor lowers Vmax, but Km remains the same, what type of inhibitor is it?
Non-competitive inhibitor
Is the regulation by covalent modification usually reversible or irreversible?
Reversible
What are the two common regulation ways of enzyme activity?
Allosteric regulation and covalent modification
Which one is faster, allosteric regulation or covalent modification?
allosteric regulation
Why phosphorating has an impact on enzyme structure?
Because phosphates are bulky negatively charged groups which affect enzyme conformation
