Week 6 Homework Flashcards
Many enzymes operate using a general acid catalysis mechanism; during this kind of reaction an amino acid R group functions as an acid by?
Donating a proton
True or false? Enzymes that require cofactors cannot function without them.
True
True or false? Enzymes speed up the rate of a reaction by decreasing the ΔG.
False
True or false? Enzymes are able to catalyze both the forward and reverse reaction.
True
An enzyme changes the free energy of the?
transition state, but not the products or reactants.
For any chemical reaction, what will happen to the rates of the forward and reverse reactions when an enzyme is added?
Both the forward and reverse rates of a reaction increase.
One mechanism enzymes use to achieve their rate enhancement of reactions is a preferential binding to the through complementary non-covalent interactions that the energy needed to reach the intermediate.
Transition state; decrease
Which events occur during lysozyme’s catalytic mechanism?
I. water is part of the enzymatic reaction
II. glutamic acid donates a proton
III. the enzyme itself is altered after the reaction
I and II
True or false? The free energy barrier in a chemical reaction must be overcome in order for products to form.
True
True or false? At a given temperature and time all molecules in a solution or a sample will have the same energy.
False
True or false? An increase in temperature can result in an increased reaction rate.
True
True or false? Lowering the free energy of the transition state can increase a reaction rate.
True
The equilibrium state of a biochemical reaction is approached ________ in the presence of a catalyst.
More rapidly
The initial velocity of an enzyme reaction (Vo) describes what?
The rate of the reaction when the substrate and enzyme are first mixed
What is an appropriate for initial rate method experiment to analyze an enzyme-catalyzed reaction?
Enzyme concentration is constant and the rate is measured at different substrate concentrations.
TRUE or FALSE. Increasing the concentration of enzyme in an assay would increase the Vmax.
True
In an enzyme reaction involving one enzyme and one substrate, the rate of the reaction depends on?
Both enzyme and substrate concentrations
The Michaelis constant, Km, is equal to the?
Substrate concentration when the rate is equal to half its maximal value
Which characteristic, if any, is a unique property of a Michaelis-Menten enzyme as compared to an allosteric enzyme?
The graph of vο vs. [S] for the enzyme is hyperbolic.
Most of the time, allosteric enzymes are composed of subunits that function and produce an enzyme activity curve that is .
Multiple, cooperatively, sigmoidal
Most of the time, Michaelis-Menten enzymes are composed of subunits that function and produce an enzyme activity curve that is .
Single, independently, hyperbolic
A plot of initial velocity vs. substrate concentration for allosteric enzymes levels off (plateaus) because?
the active sites are saturated resulting in maximal velocity
The T-form of an allosteric enzyme has affinity for the substrate and is abundant in the of substrate.
Low; absence
True or false? Both the T form and R form can exist without substrate bound to the active site.
True
True or false? The T form has a different shape than the R form.
True
True or false? A T form and R form cannot exist at the same time in an allosteric enzyme.
False
A mutation causing an amino acid change in an enzyme that affects the turnover number kcat will also affect the ________ as well
Vmax
