Enzyme Kinetics Flashcards
Enzyme Kinetics
the study of the reaction rates of enzyme catalyzed reactions
What is the rate of a reaction influenced by?
- environmental conditions like pH and temp
- concentrations of enzymes, substrates, and products
- effectors like activators and inhibitors
pH higher or lower than optimum pH can
cause the enzyme to become inactive
If pH is too extreme, it can
destroy the enzymes
Enzyme activity ______ as temperature is higher than the optimal temp, so the enzyme is ______
declines, denatured
Increasing enzyme concentration
increases enzyme activity
Increasing substrate concentration increases
the reaction rate until the enzyme is saturated, then the reaction rate becomes constant
If an enzyme is saturated then there is
far more substrate than it can deal with
Km is called the
michealis-menten constant
Km is the substrate concentration at
half Vmax
Km is _______ proportional to affinity of enzyme for substrate
inversely
High Km means
Low Km means
low affinity towards substrate
high affinity towards substrate
Michaelis-Menten Equation
used to caqlculate reaction rates
Vi= Vmax[S]/Km + [S]
Vi=
[S]=
Vmax=
Km=
initial velocity (moles/time)
substrate concentration (molar)
maximum velocity
substrate concentration when Vi is 1/2 Vmax
Effecters
a substance that can binds to an enzyme and affects the enzyme activity is called an effecter
Activators
positive effectors
Inhibitors
negative effectors
Inhibitors are
molecules that bind to an enzyme and reduce enzyme activity
Inhibitors are classified into
irreversible inhibitors
reversible inhibitors
Irreversible inhibitors
bind covalently (strongly) to the enzyme
Reversible inhibitors
bind non-covalently (weakly) to the enzyme
Irreversible Inhibitors are involved in
the binding of the inhibitor to the active site which blocks the reaction, the enzyme is damaged permanently
Ihibitors are often used as ……….. but they can also act as ……….
drugs, poisons
Irreversible inhibitors include
arsenic
snake venom
nerve gas
Reversible inhibitors can be
competitive inhibitors
noncompetitive inhibitors
Competitive inhibitors
- have a structure like a substrate
- binds to active site of the enzyme
- prevents substrate from binding
- can be released by increasing substrate concentration
Noncompetitive Inhibitors
- don’t have a structure like a substrate
- bind to the enzyme but not the active site
- change the shape of enzymes and active sites
- substrates can’t fit altered active site
- no reaction occurs
- effect is not reversed by adding substrates
