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BioChem 4511 Exam 3 - Chapter 8
Terms in this set (26)
Enzymes are ___
Generally proteins that serve as biological catalysts
Catalysts remain unchanged ___
From the beginning to the end of a reaction
Enzymes do not affect ___
How are enzymes named?
For the reaction they help carry out and then with the suffix "-ase" at the end
What are the major classes of enzyme functions?
Oxidoreductase, transferase, hydrolase, lyase, isomerase, and ligase
What are oxidoreductase enzymes?
Catalysts for redox reactions
What are transferase enzymes?
Catalysts for transfer reactions, they help the transfer of a functional group from one molecule to another
What are hydrolase enzymes?
Catalysts for the addition of water in the for of -OH^- and -H^+ to the atoms forming the bonds of either C-O, C-N, or C-S
What are lyase enzymes?
Catalysts for reactions where C-C, C-O, C-N, or C-S bonds are cleaved by means other than that of hydrolysis or oxidation
What are isomerase enzymes?
Catalysts for reactions that rearrange existing atoms in a molecule
What are ligase enzymes?
Catalysts for reactions that synthesize C-C, C-S, C-O, or C-N bonds in a reaction coupled to the cleavage of high energy phosphate bonds in ATP or another molecule
A second order reaction's rate is equal to ___
The enzymatic rate of enhancement is equal to ___
k for the catalyzed reaction / k for the non-catalyzed reaction
What factors determine if a reaction with be productive or not?
Energy of the collision and the orientation of the molecules at collision
The reaction coordinate is a term that describes ___
The overall progress of the reaction through time
What is the effect of temperatures on reaction rates?
Increases or decreases the average kinetic energy (movement) of molecules proportionally; higher => greater proportion of reactants that can react, lower => smaller proportion that can react
What is the effect of concentrations on reaction rates?
Increases or decreases proportionally change the likelihood of collisions; higher => greater chance of collisions, less => less chance of collisions
Lowering of the transitional state's free energy barrier increases the rate of the reaction in ___
The forward and backward directions
What does the transitional state theory seek to explain?
Reaction rates by assuming an equilibrium between reactants and those reactants activated to the transitional state
What is a transition state?
Unstable midway product where reactants and products are at their highest free energy level; it is short lived
How does the maximal contact between the enzyme and the reactant(s) help with catalysis?
Reduces the free energy of the transition state which stabilizes the transition state
Why do enzymes bind relatively weak to reactants?
To avoid a "thermodynamic pit" which would lower the Vmax
There is a/an ___ relationship between the rate constant and the free energy barrier
Ultimately, the binding of an enzyme to the substrate is driven forward by ___
What are the general characteristics of an enzyme?
They have a complex tertiary structure, but rely on a limited number of functional groups (side chains), coenzymes, and metal cations.
They have a catalytic site (active site) that has a high degree of specificity
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