Enzymes Flashcards
(20 cards)
Exergonic Reactions
Energy RELEASED
∆G = (-)
Endergonic Reactions
Energy REQUIRED
∆G = (+)
Oxidoreductase
Redox reactions that involve the transfer of e-
transferases
move functional group from one molecule to another
hydrolases
Catalyze cleavage with the addition of H2O
Lyases
catalyze cleavage without the addition of H2O and without the transfer of e-
the reverse reaction (synthesis) is often more important biologically
isomerase
catalyze the interconversion of isomers, including both constitutional isomers and stereoisomers
ligases
join two large biomolecules, often of the same type
kinases
ADD a phosphate group
type of transferase
Phosphatase
REMOVES a phosphate group
type of transferase
Phosphorylase
introduces a phosphate group into an organic molecule, notable glucose
Michaelis-Menten Equation
Km =
V0 =
Km =( K(-1) + K(2) )/ K(1)
the [S] at which an enzyme runs at half its Vmax
V0 = Vmax ([S]/([S]+Km))
Cofactors
metal cation that is required by some enzymes
coenzyme
organic moelcule that is required by some enzymes
Feedback Inhibition
An enzyme is inhibited by high levels of a product from later in the same pathway
Reversible inhibition
the ability to replace the inhibitor with a compound of greater affinity or to remove it using mild labrotory treatement
Competitive inhibition
when the inhibitor is similar to the substrate and binds at the active site, blocking the substrate from binding
can be overcome by adding more substrate
Uncompetitve inhibition
when the inhibitor binds only with the enzyme substrate complex
Vmax and Km both decrease
Noncompetitive inhibition
When the inhibitor binds with equal affinity to the enzyme and the enzyme-substrate complex
Vmax decreases, Km is unchanged
Mixed Inhibition
when the inhibitor binds with unequal affinity to the enzyme and the enzyme complex
Vmax decreases, Km increases or decreases depending on if the inhibitor has high affinity for the enzyme or enzyme-substrate complex
