q5 Flashcards
what is kinetics
movement
define enzyme kinetics
the rates of enzymatic reactions
relates activation energy and equilibrium
what is the basic reaction rate
S—>P
define dP
appearance over time
define dS
disappearance over time
dP/dt is the same as what
dS/dt
unit=
concentration/time
what is the normal standard
m/s
rate=
V
or
k[S]^n
describe k, the rate constant
does not depend on concentration
can be altered by catalyst or temp
determined experimentally
describe n, the order of reactant
effect of substrate concentration on rate
define and describe order
sum of exponents
affects all reactants on rate
define and describe order
sum of exponents
affects all reactants on rate
what does it mean if there is order with respect to a reactant
affects of single reactants can be seen
there is an exponent in a specific reactant
how is order found
must have a reaction and data
set 2 rates equal
solve with respect to S
use one row to solve for K
what does enzyme kinetics depend on? why can’t that be used?
[S], but it is hard to measure so [P] is used
Vo=
dP/dT
describe the michaelis-mention plot
t vs [P] plot
each line will have a different S
define Vmax
max velocity of reaction
top of curve
hyperbolic
what are kinetics used for
steady state conditions
single enzymes
single substrates
what is Km
michaelis constant
[S] at 1/2Vmax
Vo=
Vmax[S]/Km+[S]
describe the lineweaver-burk equation
reciprocal of mm plot
allows mm to be plotted linearly
what is the equation for lineweaver-burk?
what is the plot for lineweaver-burk?
what are the assumptions of velocity
rxn at an early time means no products are made
no reverse rxn from EP to ES
products are released quickly
Et is constant
steady state is reached quickly
ES is constant
what is the new assumption equation
E+S<——>ES——>E+P
describe steady state
rate of formation of ES=rate of breakdown of ES
what is the plotting criteria for steady state
ES is constant
E is constant
S is decreasing
P is increasing
what is the plotting criteria for steady state
ES is constant
E is constant
S is decreasing
P is increasing
draw a steady state graph
draw a steady state graph
Vmax=
K2[Et]
define Kcat
turnover number or catalytic constant with unit (s-1)
what does the catalytic constant do
determines how fast an enzyme works after ES is formed, but does not determine binding affinity or enzyme efficiency
Kcat/Km=
catalytic efficiency (M-s-)
define Kd
dissociation constant
inverse of binding affinity
what is enzyme efficiency controlled by
K
what do grey arrows represent? green arrows?
bioavailability
catalytic efficiency
what is activation inhibited by
substrate analogues
transition state analogues
define inreversible inhibition
non-dilutable covalent bonding/noncovalent bonding
define reversible inhibition
noncovalent and dilutable
name and describe DFP
diisopropfluorophosphate
irreversible protease inhibitor
blocks protease and phospholipase enzymes
forms bonds with certain serine residues
what are the types of reversible inhibitions
competitive
uncompetitive
mixed
Ki=
[E][I]/[EI]
Ki’=
[ES][I]/[ESI]
define competitive inhibitors
competes with substrates for active binding site
inhibitor may unbind
what is an example of competitive inhibitors
malonate-mimics succinate ligand
competes to bind succinage dehydrogenase enzyme
what does competitive inhibitors do to Km and Vmax
increases Km and does nothing to Vmax
needs higher S
Km increases to Km-app
substrate binding weakens
no physical effects
a=
I+[I]/KI
Km-app=
Km(1+[1]/KI)
describe uncompetitive inhibition
decrease Km and Vmax, but slope stays
binds away from active site
binds ES
Km decreases to Km-app
LB stays the same
describe mixed inhibition
decreased Vmax, either for Km
binds away from activation site
binds enzyme or ES
affects S binds
Ki- binding affinity for I for E
Ki’- binding affinity for I for ES
describe noncompetitive inhibitor
decreased Vmax, no change in Km
mixed inhibition
does not bind active site
causes conformational change and affects activation site
Ki=Ki’
