Kinetics Flashcards
general emzyme reaction
E + S -> ES -> EP -> E + P
equilibrium binding constant
k1/k-1 = [E][S]/[ES] (faster than k2)
Michaelis menton rules
[S]>[E] ([S]free =[S]total)
All ES complexes have the same rate of reaction
Haldane’s steady state assumption: rate of ES formation=breakdown
Initial rate - [S] doesn’t change much
Reverse reaction doesn’t occur
Michaelis menton equation
Vobs = (Vmax[S])/(Km + [S])
Vobs
=k2[ES}
Km
=k-1/k1=[E][S]/[ES]
Briggs + Haldane steady state
Km=(k-1+k2)/k1 - fast k2
as [ES] made, [E][S] reformed?
small k2 reverts to MM
Km
low=high affinity, characterises one enzyme-substrate pair
Vmax
=kcat[E]t
kcat
number of substrate molecules converted to product, per enzyme, per time
Comp inhibitor reaction
E + I -> EI + S -> no reaction
Kmapp
=aKm
a
= 1 + [I]/Ki
Comp inhibitor via alternate substrate reaction
E + I -> EI + S -> EJ + S
Mixed non-comp reaction
E + S -> ES + I -K’1> ESI -> no reaction
E + I -K1> EI
pure non-comp inhibition
a=a’, Km stays the same
uncompetitive inhibitor
Binds to transition state/enzyme-ligand
E + S ES + I -K’1> ESI -> no reaction
Parellel lines on burk-weaver
Multiple substrates reaction
A + B -> P + Q
P-X + B -> P + B-X
Sequential binding
ordered or random
Ordered binding
E + A -> EA + B -> EAB-EPQ -> P + EQ -> Q + E
LWB intercepts
Random binding
(E + A -> EA + B) OR (E + B -> EB + A) -> EAB-EPQ -> (P + EQ -> Q + E) OR (Q + EP -> P + E)
Non sequential/ping pong
E + A -> EA-FP (covalent catalyst) -> P, F + B -> FB-EQ -> Q + E
Parallel LWB
Switches between two states, substrates bind at different times
