Enzymes And Rates Of Reaction Flashcards
Why are enzymes studied
What do enzymes do
What are the characteristics of enzymes
What is the definition of an enzyme, active site and substrate
What are the characteristics of the active site of an enzyme
Name the 3 models used to describe how enzymes bind to substrates
What is the lock and key model
Describe the induced fit model
What does hexokinase do
How are active sites of enzymes specific to their substrates
What is geometric specificity
Give an example of a permissive enzyme
What is stereospecificty
How do you determine whether an enantiomer is an R or S enantiomer
Find chiral centre first
What is YADH
How do you determine the priority of hydrogens in a prochiral molecule
React molecule with NAD
How are enzymes classified
What are the six classes of enzymes and the numbers they are assigned
Oxidoreductases= 1
Transferases= 2
Hydrolases = 3
Lyases = 4
Isomerases = 5
Ligases = 6
What do oxidoreductases do
What do transferases do
What do hydrolases do
What do lyases do
What do isomerases do
What do ligases do
What are cofactors
What are prosthetic groups
What are cosubstrates
What is a holoenzyme
What is an apoenzyme
What is a coenzyme
An organic molecule that helps facilitate the action of enzymes
Why are vitamins needed
Name some examples of cofactors
How are enzymes linked to health
What are some examples of enzyme markers and what do they mark
What does thermodynamics tell us
How may a reaction progress steps wise
What is the general rate equation
What is the overall order of a reaction
What is meant by the order of a reaction
What is a first order reaction
Rate is directly proportional to concentration (as conc increases, rate increases)
Half life unaffected by conc
What is a second order reaction
What is a third order reaction
Or two molecules of one reactant and one of another or it involves three molecules of a single reactant
What is the rate equator for a first order reaction
Rate (or v)= k[A]
What is the rate equation for a reaction that is reversible
(Only reversible reactions have an equilibrium position)
What are the possible rate equations for a second order reaction
What is instantaneous rate
What is the integrated law for first order reactions using logarithms
[A]0 is initial conc of reactant
k is the rate constant
What is the integrated law for first order reactions using exponential
What is the graph shape for an ln[A]-time graph for a first order reaction and what does the gradient mean
What is the shape of a conc-time graph for a first order reaction
What is the shape of a rate-conc graph for a first order reaction
What is the shape of a conc-time graph for a second order reaction
What is the shape of a rate-conc graph for a second order reaction
What is the shape of a conc-time graph for a zero order reaction
What is the shape of a rate-conc graph for a zero order reaction
What is meant by half life
How do you calculate the half life for a first order reaction
What is the integrated rate law fora second order reaction
What are integrated rate laws used for
integrated rate laws express the reaction rate as a function of the initial concentration and a measured (actual) concentration of one or more reactants after a specific amount of time (t) has passed; they are used to determine the rate constant and the reaction order from experimental data.
What is the shape of a 1/[A]-time graph for a second order reaction
How do you calculate the half life of a second order reaction
What is the rate determining step
Slowest step in a multistep reaction
How can rate laws be determined experimentally
What is collision theory
What is an ineffective collision
If molecules collide in the wrong orientation and/or have insufficient kinetic energy
Draw and explain an potential energy profile diagram
What happens if collision energy >Ea
What happens if collision energy <Ea
What is the potential energy profile for an exothermic reaction
Ea for forward exothermic reaction is < Ea for backward reaction
What is the potential energy profile for an endothermic reaction
Ea for forward exothermic reaction is > Ea for backward reaction
Draw the Maxwell - Boltzmann distribution curve and explain it
At a temperature T1, a certain fraction of the reactant
molecules have sufficient K.E., i.e. K.E. > Ea.
At a higher temperature T2, a greater fraction of the
molecules possess the necessary activation energy, and the reaction proceeds at a faster rate.
Write the Arrhenius equation
A and Ea= Arrhenius parameters
Ea units kj mol-1
A =same units as k
k= rate constant
R =8.314
T =temp in Kelvin
What can be derived from an Arrhenius plot
What does it mean if an Arrhenius plot has a steep or shallow slope
How do you find the activation energy for a reaction occurring at 2 different temps
How can you increase the rate of reaction
What is a transition state
It is a transient configuration of atoms where the bonds in the reactants are partially broken, and new bonds in the products are partially formed. This state is often denoted by the double dagger symbol
What is meant by a zero order reaction
Conc has no effect on rate
Half life dec as conc dec
What are the characteristics of the active site of an enzyme
How do enzymes increase the rate of reaction
What does metastable mean
stable provided it is subjected to no more than small disturbances
Draw a potential energy profile including the transition state
Write the general equation for a reaction including is transition state
What is meant by this symbol
Activation energy
How can the concentration of the transition state be used to find the rate of reaction of a catalysed reaction
How can the concentration of the transition state be used to find the equilibrium constant of a catalysed reaction
How can the rate constant of catalysed reaction be found
Recall the eyring equation and what it tells us
What is the relationship between free energy change and the rate constant
What is the linear form of the eyring equation and what does it look like graphically
What can be found from the slope and y intercept of the graph
How do enzymes increase the rate of reaction
What is meant by this symbol and how is it calculated
Change in Ea
Explain the pathway of catalysis using this diagram
How do enzymes decrease Ea
Draw the potential energy diagram for when there is no enzyme
Draw the potential energy diagram for when the enzyme is complimentary to the substrate
Draw the potential energy diagram for when the enzyme is complimentary to the transition state
What rate law does enzyme bound substrates follow
First order
Why is there a decrease in entropy when the substrate binds to an enzyme
Draw and label a reaction profile for a reaction with multiple steps
What is tyrosyl tRNA synthase
What does this symbol tell us
What does this symbol tell us
What are transition state analogues
Can synthesise molecules that have a similar structure to the transition state that are stable
Since transition state molecules can’t be isolated but can be predicted
What can transition state analogs be used for
What can catalytic antibodies be used todo
What are abzymes and what are they used for
What is the Hammond postulate
( so their interconversion would only require some molecular reorganisation)
It can be used to predict the structure of the transition state
How does the Hammond postulate link to endo and exothermic reactions
What is desolvation
How does distortion occur to substrates when they bind to enzymes
This achieves a transition state with less energy (more stable)
How do enzymes increase the chance of a reaction occurring
What are the different types of enzyme assays
What are enzyme assays used for
What factors need to be taken into account when developing an assay
What are the factors that can affect an assay
What do the different curves on this graph mean
What are the units used to measure activity in an assay
What should be considered during assay development
What are continuous assays
What methods can be used to measure change in [s] in a continuous assay
When is using a spectrophotometer appropriate for an assay
What are the limitations of using a spectrophotometer in an enzyme assay
Limitations of spectrophotometry include a relatively low sensitivity and selectivity. It may thus be difficult to detect very low concentrations of an analyte or distinguish the analyte from other substances that absorb light on the same wavelength.
What are coupled reaction assays
What considerations should be made when using a coupled reaction
What is a fluorimetric assay
What are chemiluminescent assays
What are discontinuous /fixed time assays
What methods can be used to measure fixed assay data
What may interfere with your assay
Have can you further optimise your assay
What is the difference between continuous and discontinuous assays
Enzyme assays can be split into two groups according to their sampling method: continuous assays, where the assay gives a continuous reading of activity, and discontinuous assays, where samples are taken, the reaction stopped and then the concentration of substrates/products determined.
