chapter 11 enzymes part 1 Flashcards
who discovered the enzume
buchner
what Ea
the activation energy needed to reach and overcome a high energy transition state
wht determines if a reaction will occur or no
delta g
- spontaneous yes
nonspontaneous no
why is low Ea better
faster rate and the molecules can acheive that energy
an enzyme is also known as a
catalyst
what do enzymes do
they speed up the reactions
what has to happen for an enzume to catalyze a reaction
the free energy needs to de
what are the dos of enzymes
lower Ea
speed up time = speed up reaction
stabilize the transition state
what are the donts of the enzymes
dont change the delta g
don’t change the Keq(equilibrium constant )
what conditions do enzymes catalyze
mild conditions
what does it mean if an enzyme is stereospecific
the enzyme can catalyze reactions involving specific stereoisomers
explain the lock and key model of enzyme
- enzyme is the lock substrate is the key
- fischer
- selectivity of chymotrypsin, trypsin, elastase
what are some limitations with lock and key model
- doesn’t account for diverse substrates
- doesn’t account for enzymes stabilizing transition state of the reaction
explain the induced fit model of enzyme
-koshland
- Substrate binds and causes a conformational change in the active site of the enzyme and it stabilizes the TS
- more than 1 s can be recognized by certain enzymes bc E can fit around different S
what are cofactors and what is their importance
- ## non protein component that helps enzymes function
what are some examples of cofactors
metal ions
small organic molecules like coenzymes(vitamins)
- apoenzyme
what makes a holoenzyme
apoenzyme + cofactor
what factors affect enzyme activity
-temp
pH
cofactors
allosteric effectors
poiosns/ inhibitors
what are the enzymatic catalysis mechanisms (6)
proximity effects
general acid base catalysis (gaba)
covalent catalysis
electrostatic stabilization
preferential stabilization of strained transition state
metal ion catalysis
what is the proximity effect
positioning molecules close together for a rxn
what is GABC
donating/ accepting an H+ by providing weak acid base to stabilize an unstable TS and thus lowering Ea
what is covalent (nucleophillic) catalysis
enz active site provies nucleophile that forms a covalent Enz-s adduct that alters the reaction
what is preferential stabilization of strained transition state
lowering Ea by stabilizing a conformationally unstable TS
what is metal ion catalysis
catalyzing rxns by charge shielding; polarizing water to make it a better nucleophile etc
- bind substrates to orient them for catalysis
what does freezing out the rotational translational motions do
increase the rate by a lot
what are the amino acid side chains that participate in GABA
