Module 3 Flashcards
What are the 6 classes of enzymes?
Oxido-reductase
Transferase
Hydrolase
Lyase
Isomerase
Ligase
Class of enzymes capable of catalyzing the reaction of joining two large molecules
Ligase
Class of enzymes which catalyze the cleavage of covalent bond using water
Hydrolase
Class of enzymes which mediate transfer of electrons from one molecule to another.
Oxido-reductase
Class of enzymes that catalyzes the formation of double bonds by removal of groups or addition of groups to double bonds
Lyase
Class of enzymes which catalyze intramolecular rearrangements
Isomerase
Class of enzymes responsible for catalyzing redox reactions.
Oxido-reductase
Class of enzymes which catalyze the transfer of a group of atom from a donor substrate to an accepting compound.
Transferase
Enzymes that catalyze the joining of specified molecules or groups
Lyase
Characteristic of enzyme reactions which became the basis for the “lock and key” model.
Geometric Complementarity
Happens when amino acid residues
that form the binding site are
arranged to specifically attract the
substrate
Electronic Complementarity
There are four digits in the Enzyme Code Notation. Name what each digits stand for.
1st - class name
2nd - subclass
3rd - accepting functional group
4th - accepting molecule
First digit of Enzyme Code Notation of the enzyme DNA polymerase
2
First digit of Enzyme Code Notation of the enzyme carbonic anhydrase
4
First digit of Enzyme Code Notation and full name of the enzyme TPP
- (Triose phosphate isomerase)
First digit of Enzyme Code Notation of the enzyme pyruvate carboxylase
6
First digit of Enzyme Code Notation of the enzyme pyruvate dehydrogenase
1
First digit of Enzyme Code Notation of the enzyme acetylcholinesterase
3
T or F: Coenzymes may be an organic or organometallic molecule
True
T or F: Pure metal ions are not considered coenzymes
True
T or F: Pure metal ions cannot be cofactors
False
This compound is an obligatory oxidizing agent in the alcohol dehydrogenase reaction.
NAD+
True or False:
I. Both enzymes and coenzymes are chemically changed by the reaction.
II Both enzymes and coenzymes are not chemically changed by the reaction.
III. Coenzymes are chemically changed by the reaction.
I. F
II. F
III. T
Coenzymes are __________ in order to complete the catalytic cycle.
Regenerated/returned to its original state
It is the enzymatically inactive protein resulting from the removal of a cofactor
Apoenzyme
It is a catalytically active enzyme-cofactor
Holoenzyme
What are the two factors influencing the activity of enzymes?
Temperature and pH
The rate decline begins in the temperature range of ____________.
50 °C to 60 °C
The optimal pH for most enzymes.
6 - 8
T or F: The free energy of catalyzed reaction is higher than uncatalyzed reaction.
False. There is no difference.
T or F: A catalyzed reaction has lower activation energy than an uncatalyzed reaction does.
True.
T or F: Catalysts changed the equilibrium of the reactants and products, favoring the formation of products.
False.
Catalysts usually act by forming a ___________________ with the reactant, thus stabilizing the __________________.
transient complex; transition state
This describes the region of the enzyme in which the substrate binds.
Active site
Characteristic of the active site wherein it only accept ONLY ONE type of molecule.
Absolute Specificity
T or F: Active sites with absolute specificity will never discriminate between the enantiomers of a compound
False.
Note: Enantiomers -> Levorotatory or Dextrorotatory
T or F: The active site is the largest part of the enzyme.
False. It is relatively small.
What are the three models of the substrate-enzyme binding?
- Lock and Key Model
- Induced Fit Model
- Transition State Model
This model assumes that an active site is flexible and undergoes conformational change until the substrate is completely bound.
Induced Fit Model
The active site is able to accept only a specific type of substrate
Lock and Key Model
Active site and the binding portion of the substrate are not exactly complementary
Induced Fit Model
T or F: In the Induced Fit Model, after the products move away from the enzyme, the enzyme will retain its shape.
False. It returns to its initial shape.
Five main types of catalytic mechanisms.
- Acid-base catalysis
- Covalent catalysis
- Metal ion catalysis
- Proximity and orientation effects
- Preferential binding of the transition state complex
This catalysis requires a nucleophile to form transient covalent bonds between enzyme and substrate, lowering the activation energy.
Covalent catalysis
This type of catalysis makes the activation energy higher than uncatalyzed reaction.
No answer. All catalysts lower the activation energy.
