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CH. 2 Enzymes

Terms in this set (39)

Oxidoreductases
Enzyme class responsible for catalyzing redox rxns that involve the transfer of electrons
Transferases
Enzyme class responsible for transferring a functional group from one molecule to another molecule
Hydrolases
Enzyme class that catalyzes cleavage of bonds with the addition of water
Lyases
Enzyme class that catalyzes the cleavage without the addition of water and without the transfer of electrons
A type lyase responsible for the synthesis of smaller compounds
Synthase
Isomerases
Enzyme class that catalyzes the inter-conversion of isomers, including both constitutional isomers and stereoisomers
Ligases
Enzyme class responsible for joining two large biomolecules often of the same type
In an exergonic rxn, delta G is positive or negative?
Negative
Enzymes increase or decrease the activation energy of biological rxns?
Decrease
True or false, enzymes do NOT alter the free energy of a rxn (delta G) or enthalpy (delta H)
True
True or false, enzymes do NOT change the rate (kinetics) at which equilibrium is reached
False
The induced fit model hypothesizes that ___
The enzyme and substrate undergo conformational changes to interact fully
This theory hypothesizes that the enzyme and substrate are exactly complementary
Lock and key theory
In the presence of an enzyme, substrate concentration increases, the reaction rate _____ until a max value is reached
Increases
A michaelis-menten plot is in the shape of a
hyperbola
______ display a sigmoidal curve because of the change in activity with substrate binding
Cooperative enzymes
_____ is characterized by the ability to replace the inhibitor with a compound of greater affinity or to remove it using mild laboratory treatment
Reversible inhibition
During competitive inhibition, the inhibitor binds at the?
active site
Can competitive inhibition be overcome? If so, how?
Competitive inhibition can be overcome by adding more substrate
In which type of inhibition is vmax unchaged and Km increased?
competitive
In which type of inhibition does the inhibitor bind with EQUAL affinity to the enzyme and the enyzme-substrate complex?
non competitive
How is vmax affected during non competitive inhibition?
decreased
Km is unchanged in which type of inhibition? and Why
non competitive, b/c the inhibitor binds with equal affinity to both the enzyme and the enzyme-substrate complex
______ results when the inhibitor binds with unequal affinity to the enzyme and the enzyme-substrate complex
Mixed inhibition
In mixed inhibition, Km is increased or decreased depending on_____?
Whether or not if the inhibitor has higher affinity for the enzyme or enzyme-substrate complex
Km and Vmax both decrease in which type of inhibition?
Uncompetitive
In uncompetitive inhibition, the inhibitor binds to___?
The enzyme-substrate comlex
This type of inhibition alters the enzyme in such a way that they active site is unavailable for a prolonged duration or permanently; new enzyme molecules must be synthesized for the reaction to occur again
Irreversible inhibition
Zymogens
A type of regulatory enzyme that is secreted in an inactive form and is activated by cleavage
Enzymes with dehydrogenase or reductase in their names, usually belong to which class of enzymes?
Oxidoreductases
Enzymes with peptidase, nuclease or lipase in their name usually belong to which class of enzymes?
Hydrolases
Why does Km remain unchanged during non competitive inhibition?
Because any copies of the enzyme that are still active maintain the same affinity for their substrate
In the absence of an enzyme, the optimal temperature for a rxn is higher or lower than with an enzyme?
higher
The substrate concentration at which half of an enzyme's active sites are full is known as
Km
A higher Km is associated with higher or lower affinity of the enzyme for its substrate?
lower
A plot displaying 1/V vs 1/[s] is called?
line-weaver burk plot
The x-intercept on a line-weaver burk plot is?
-1/Km
1/vmax is the y intercept on which type of graph?
lineweaver burk
Km\Vmax is the slope on which type of graph?
lineweaver burk
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