enzymes Flashcards
enzymes are ____ catalysts
biological
biological catalysts have milder reactions compared to chemical catalysts and have greation reaction _____ with respect to substrates and products (have capacity for regulation)
specificity
why is it important that proteins and enzymes are regulated
to stay away from disease state but also to facilitate interactions (can change structure or use cofactors, remove things physically, storage or phosphorylation)
enzymes ____ reaction rates compared to uncatalyzed reactions and chemically catalyzed reactions n
increase
enzymes use _____ conditions comared to chemical catalysis
milder
nitrogen fixation can be catalyzed by
- lightning
- haber process (150-250 atmospheres)
- symbiotic bacteria in root nodules of legumes
enzymes have reaction specificity as well as _____ specificity and ____
geometry (of chemical structures) & stereo
the regulation of the activity of an enzyme by binding of an inhibitor or activator at a site on the protein separate from the substrate binding site
allostery
regulation: phosphorylation, acetylation, and removal of inhibitory peptides
covalent modification
regulation of enzymes: assembly into ____ complexes
macromolecule
regulation of metabolic pathway by the inhibition of enzyme that catalyzes a reaction early in the pathway by the product of the pathway
feedback inhibition
the ____ is missing a cofactor or co enzyme
apoenzyme
when a ____ contains a cofactor or coenzyme and can act on substrate
haloenzyme
common names of enzymes end in
ase
some enzymes need help to catalyze their reactions so they use a ____
cofactor
co factors can be
small molecules or metal ions
organic cofactors derived from vitamins, may associate transiently or be tightly linked
coenzymes
delta G double dagger is
activation energy barrier
the standard free energy change from product to substrate is
standard free energy change
delta G’° is how ___ that the reaction will happen
likely
delta G double dagger is how ___the reaction will take place
fast
enzymes can only change which delta G
delta G double dagger
a large delta G double (large activation barrier) dagger means ___ k and ___ reaction
small (rate constant) , slow
delta G’° < 0 has more ___ than __ at equilibrium (forward rxn is favorable)
P S
if delta G double dagger is big enough it will never reach equilibrium no matter how ____ delta G’°
negative
enzymes low ___
deltaG double dagger
ES and EP can be considered __ ___
reaction intermediates
the step with the highest energy barrier is (has smallest k)
rate limiting step
enzymes catalyze both forward and ___ reactions
reverse
what is a catalyzed reaction step wise
S+E <—> ES <—-> EP <—> P + E
an enzymes active site should be complimentary to the _____ state to break up products
transition
if the enzyme is complimentary to substrate it will stabilize ___ state which increases the delta G double dagger significantly
ES
catalytic power of enzymes derived from
- binding energy
- binding is optimized to the transition state
conversion from two free reactants to one single transition state is entropically _____
unfavorable
uncatalyzed unimolecular reactions has a flexible reactant —> rigid transition state; the conversion is entropically _______
unfavorable
enzymes uses the binding energy of substrates to organize reactants to fairly rigid ES complex; when is entropy cost paid
during binding
interactions between S and H2O are replaced by S and E; increases reaction rate
desolvation of substrates
catalysis involves formation of ____ bonds
covalent
specific acid base catalysis means that donation/ abstraction of charge is carried out by _____
water
occurs frequently with general acid base catalysis and results in new reaction pathway that are uncatalyzed
covalent catalysis
as long as the steps involved in forming and breaking the covalent bonds are ____ than the uncatalyzed, catalysis will occur
faster
