Enzymes Flashcards
do not impact the thermodynamics of a biological reaction, help the reaction proceed at a much faster rate, delta Hrxn and equilibrium position do not change
Catalysts
- lower the activation energy
- increase rate of reaction
- are not changed or consumed in reaction
- are pH and temp sensitive, optimal activity at specific pH ranges and temps
- do not alter the overall delta G of the reaction
- are specific for a particular reaction or class of reactions
Enzymes
catalyze oxidation-reduction reactions
oxidoreductase
catalyze the movement of a functional group from one molecule to another
transferase
catalyze the breaking of a compound into two molecules using the addition of water
hydrolases
catalyze the cleavage of a single molecule into two products
lyases
catalyze the rearrangement of bonds within a molecule
isomerases
catalyze addition or synthesis reaction and generally require ATP
ligases
molecule upon which an enzyme acts
substrate
generally inorganic molecules or metal ions
cofactors
small organic groups, vast majority vitamins and derivatives or vitamins
coenzymes
What is the only way to increase Vmax
increase [enzyme]
describes how the rate of the reaction (v) depends on the [ E] and [S]
Michaelis-Menten equation
[S] at which half of the enzyme’s active sites are full
Km Michaelis Constant
double reciprocal graph of the Michaelis Menten equation, useful when determining type of inhibition enzyme is experiencing
Lineweaver-Burk Plot
1/-Km
x intercept LBP
1/Vmax
y intercept LBP
regulation by products further down a given metabolic pathway
feedback regulation
simply involves occupancy of the active site, can be overcome by adding more substrate. Increases Km
competitive inhibition
bind to an allosteric site, inducing change in enzyme conformation. Cannot be overcome by adding more substrate. Decreases Vmax
Noncompetitive inhibition
inhibitor can bind to either the enzyme or the enzyme-substrate complex, but has different affinity for each. Can increase or decrease Km and decreases Vmax
mixed inhibition
bind only to the enzyme-substrate complex and essentially lock the substrate in the enzyme, lowers Km and Vmax
uncompetitive inhibition
inactive form of enzymes, that must be altered before becoming active.
Zymogen
active site is made unavailable for prolonged period of time, or enzyme is permanently altered
irreversible inhibition
