Lecture 10 - Enzyme Mechanisms Flashcards
Which enzyme catalyzes the polymerization of nucleotides to form DNA?
DNA polymerase
Why are enzymes central to all biochemical processes?
Enzymes show greater substrate specificity, and have an optimal arrangement of catalytic groups for chemical reaction
Enzymes increased reaction rates but not reaction equilibria
List the inorganic ions that serve as cofactors for enzymes
Cu2+ Fe2+ or Fe3+ K+ Mg2+ Mn2+ Mo Ni2+ Zn2+
Interaction between substrate and enzyme is mediated by what?
The same noncovalent forces that stabilize protein structure
Lowers energy of transition state making it easier to form
Transition state stabilization
Arranges atoms for optimal activity
Orientation
Binding removes interactions with solvent (water)
Desolvation
Substrate binding changes conformation of enzyme
Induced fit
What kind of catalysis pushes or pulls a proton?
Acid – base catalysis
What kind of catalysis adducts or intermediates?
Covalent catalysis
What kind of catalysis involves Lewis acid and redox agents?
Metal ion catalysis
Energy derived from ES interaction is called what?
Binding energy (ΔGB)
True or false? Enzymes use binding energy to achieve substrate specificity and to stabilize the transition states through noncovalent interactions.
True
What kind of bonds or interactions are considered non-covalent interactions?
Hydrogen bonds
Ionic interactions
Hydrophobic interactions
True or false? The mechanism of enzyme binding is a “lock and key” mechanism.
False, it is NOT
True or false? Enzymes bind the transition state with a greater affinity than either substrates or products.
True
Transition state analogues are good ________ of enzymes
Inhibitors
Class of enzymes involved in transferring electrons
Oxidoreductases
Class of enzymes involved in the group transfer reactions
Transferases
Class of enzymes involved in hydrolysis reactions
Hydrolases
Class of enzymes involved in the addition of groups to double bonds or double bond formation by removing groups
Lyases
Class of enzymes involved in transfer of groups within a molecule to give an isomer
Isomerases
Class of enzymes involved in the formation of C – C, C – S, C – O, and C – N bonds by condensation reactions coupled with ATP cleavage or similar cofactor
Ligases
What’s the relationship between activation energy and rate?
The relationship is inverse and exponential. As activation energy decreases, the rate increases.
