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23 Cards in this Set
- Front
- Back
oxidoreductase |
catalyze oxidation-reduction reactions that involve transfer of electrons |
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transferases |
move a functional group from one molecule to another |
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hydrolases |
catalyze cleavage with the addition of water |
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lyases |
catalyze cleavage without addition of water and without the transfer of electrons. reverse reaction (synthesis) often more important biologically |
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isomerases |
catalyze interconversion of isomers, including both constitutional isomers and stereoisomers |
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ligases |
responsible for joining two large biomoleculues, often of the same type |
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exergonic reactions |
release energy, delta G is negative |
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enzymes act by |
stabilizing transition state, OR providing favorable microenvironment, OR bonding with the substrate molecules |
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site of catalysis on enzyme |
active site |
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lock and key theory |
enzyme and substrate are exactly complementary |
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induced fit model |
enzyme and substrate undergo conformational changes to interact fully |
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saturation kinetics |
as substrate concentration increases, reaction rate does as well until a maximum value is reached |
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Km |
concentration of substrates when the reaction reaches half of Vmax |
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Vmax |
maximum rate of reaction, when enzyme is totally saturated with substrate |
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feedback inhibition |
regulatory mechanism whereby catalytic activity of an enzyme is inhibited by the presence of high levels of a product of the reaction |
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reversible inhibition |
ability to replace the inhibitor with a compound of greater affinity, or to remove it using mild laboratory treatment |
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competitive inhibition |
inhibitor is similar to the substrate and binds at the active site. can be overcome by adding more substrate (vmax unchanged, km increases) Reversible |
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non-competitive inhibition |
inhibitor binds with equal affinity to the enzyme and the enzyme-substrate complex Vmax decreases, Km unchanged Reversible |
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mixed inhibition |
inhibitor binds with unequal affinity to the enzyme and the enzyme-substrate complex vmax decreased, Km increased or decreased depending on if the inhibitor has higher affinity for enzyme or enzyme-substrate complex Reversible |
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uncompetitive inhibition |
inhibitor binds only with the enzyme-substrate complex Km and Vmax both decrease Reversible |
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irreversible inhibition |
alters enzyme in such a way that active site is unavailable for a prolonged duration or permanantly |
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allosteric site |
can be occupied by activators, increasing affinity or enzymatic turnover |
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zymogens |
regulatory enzymes that are secreted in an inactive form, activated by cleavage |