Chapter 7 Kinetics and Regulation Flashcards
What is the first order reaction, and what is the proportionality constant unit?
- This is when the velocity of a reaction is directly proportional to reactant concentration and it uses the units s^-1
What is the second order reaction’s proportionality constant units?
its per molar per second, M^-1s^-1
How is enzyme kinetics measured ?
When you measure velocity as a function of substrate concentration with a fixed amount of enzyme
What is the difference between K1 and K^-1 and K2
-K1 is how fast the enzyme binds
-K^-1 is how fast the Enzyme disassociates
-K2 is how fast the substrate is converted into product
How is initial velocity determined ?
- it is determined by measuring product formation as a function of time and then determining the velocity soon after the reaction has started
What is the Michaelis Menten equation
V0=Vmax([S]/[S]+Km)
-and we ignore the bottom [S] if it is much much smaller than the Km.
What is the Lineweaver Burk equation?
1/Vo=Km/Vmax*1/S+1/Vmax
k2 is also known as ?
kcat
If [E]T is known what equation is useable ?
Vmax=k2[E]T
If the [S]«Km, what can we assume about the [E]T
we can assume that free enzyme [E]~[E]T
Kcat/Km is a measure of ______________
catalytic efficiency
The _______Kcat over the _________ the Km better the result. We always want a ________Kcat and a ________ Km
Higher, smaller,Higher,smaller
What is the rate limiting step?
The rate of formation of the enzyme substrate complex,K1
Diffusion limits the value of K1 around what value
~10^8-10^9 s^-1M^-1
-What are sequential reactions?
It is a formation of ternary complex consisting of thee two substrates and the enzyme
What are double displacement reactions? What are the also known as?
it is a formation of a substituted enzyme intermediate, they are also known as ping-pong reactions
What are allosteric enzymes and what do they do?
-They are catalysts and information Sensors
-it controls the flux of biochemical reactions in metabolic pathways
- Without them metabolic chaos would occur
What allows the allosteric enzyme to do generation of complex metabolic pathways ?
Their regulatory properties allow for that
_________________catalyze the committed step of metabolic pathways,________________ facilitate the remaining steps
Allosteric enzymes, Michaelis Menten enzymes
How does the synthesizes of F get regulated?
By the feedback inhibition , it sends a message to A when there is too much F being made and it eventually inhibits the process.
How does the pathway product F inhibit enzyme e1
it binds to the regulatory site on the enzyme that is distinct from the active site
Which type of model describes the behavior of allosteric enzyme
The concerted model
What are the features of the concerted model
-The enzyme exists in two different quaternary structures, designated T(tense) and R(relaxed)
-T and R are in equilibrium , with T being the more stable state
-The R state is enzymatically more active than the T state
-All active sites must be in the same state
What will help favor the conversion of more enzymes to the R state.
The disruption of T<–>R equilibrium by the binding of substrate
Which state will most enzymes be in as concentration increases?
The R(relaxed) state
what disrupts the R<–>T equilibrium when they bind enzyme
Allosteric regulators
What stabilizes the T and R state
-Inhibitors stabilize T state
-Activators stabilize R state
What is the disruption of T<–>R equilibrium by substrate called
Homotropic effect
What is the disruption of T<–>R equilibrium by regulators called
Heterotropic effect
What is the sequential model
it is a model for allosteric enzymes that proposes subunits undergo sequential changes in the structure
