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73 terms

Bio Chem Kinetics

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Kinetics
the rate of enzyme catalyzed rxn/ how fast or slow
Why is kinetics important?
the rate of enzmyes with different substraes is imporatnat for drug desgn (in the presences of inhibitor)
Ex of enzymes that want to slow down a rxn?
Lipitor
Ex of drugs that want to stop rxn?
Anticancer and antibiotics
What does the michaelis-mention eq do?
explains what you see experimentally when you do an enzyme catalzyed rxn
What does the horizontal slope of the hyperbola graph of MandM Equation stand for?
Vmax meaning its going as fast as it can go and its saturated
What type of dependence does Vo have on [S]? Meaning as [S] increase, what happens toVo?
Zero order, no change to Vo
What is the bottom linear line represent of the MandM eq in terms of dependency?meaning?
Represents the 1st order dependency of Vo on [S] meaning as [s} increase the Vo increases
What is Km?
Michalis constant, interms of CONCENTRATION where you are AT 1/2 vmax
What is Vo?
Measure of initial rate (first 10% of the rxn)
Why do you only look at the 1st 10% of the rxn?
To ignor the back reaction
What is the M and M equation (Michaelis Menten Eq)
Vo= (Vmas x [S]) / (Km + [S])
Whats the new equation as [S]<<<Km? And why/
(Vmax/Km)x (S) because the bottom S becomes negligable
What does the equation (Vmax/Km)xS represent in the graph and what conditions are these?
Corresponds to the First bottom Linear line when [S] <<< Km (Shows 1st order of dependence)
What is the equation when S>>>Km? and Why?
Vo=Vmax because the Km value is negligable
What does the equation Vo=Vmax represent on the M and M graoh?
Represents the horizontal linear line for Vmax
What does the eq Vo=Vmax say about the dependency?
There is no dependence of rate of Vo on S
What are the units associated with Km?
uM or mM or M
What does the Km gauge?
Gauges how tightly an enzyme binds its substrate
What does a low Km mean?
Binds substrate more tightly to the enzyme making it prcocess less substrates
What kind of saturation is associated with low Km?
readily saturate
What does a high Km mean?
binds the substrate more losely to the enzyme so process more substrates/metabolites
What type of saturation is associated with a high Km?
Its more readily saturated
What type of Km represents the "on" switch?
High Km process more substrate
What kinetic parameter can be a way of regulating a rxn?
adjusting the Km values
What values can enzymes change in response to some bio happenings?
Km valuse because in the same rxn you can have different Kms
What do both hexokinase and gluockinase do?
Put phosphate on glucose
Where is hexokinase and glucokinase found?
Hexo is found everywhere BUT the liver and gluco is found in the LIver
What type of Km values do hexokinase and glucokinase have?
HExo=Low Km (Proocess less and "sucks up" ess glucose) Gluco=High KM (sucks up excess glucose
Kcat/Km
specificty constant- takes into account BINDING and TURN oVer
What does Kcat take into account?
Turn over ONLY
What does Kcat/Km give an indicator for?
how fast the product is formed from the E+S free in solution
What does Kcat/Km help determine?
Which substrate is better for an enzyme if there is more than one substrate
What valuse of Kcat/Km indicates the best substrate?
HIGH kcat/km
Types of bonds found in Reversible and Irreversible inhibtition
Irriversible DOES have covalent bonds btween the E and the inhibitor when eversible doesnt
What types of inhibitor is 5 Florouricil? and what does it inhibit?
Irreversible ihinibitor of thymidylate synthease
What type of inhibitor is Methlytrexate and what does it inhibit?
Reversible inhibitor of dihydrolate reductase
What do Methlytrexate and 5 Florouricil do?
interphere with DNA synthesis in papidly growin cells including hair and stomach cells
What does the line weaver burk plot do?
Makes the M and M graph linear and makes it easier to read
What is the slope of the Line Weaver Burk Plot?
Km/Vmax
What is the Y intercept of Line Weaver Burk Plot?
1/Vmax
What is the lable for the Y intercept of Line Weaver Burk Plot?
1/vO
What is the Xintercept for the Line Weaver Burk Plot?
-1/km
what is the x lable for the Line Weaver Burk Plot?
1/[s]
What is the Line Weaver Burk Plot equation?
(1/Vo)= (Km/Vmax) (1/s) + (1/Vmax)
What type of inhibitor is a competive inhibitor?
Reversible
What doe competivite inhibitors resemble?
Substrate
Where do competive inhibitor bind?
at the active site BUT are NOT processed- just block the actie ste
What changes and stays the same as the amount of competive inhibitor is increase?
(1/vmax) is constant and (-1/Km) becaome less negative/increases [Kapparent increases)
Why does V max remain constant?
Because if there is a ridiculous high amt of substrate, then the competive inhibitor is going to basically not beat out all the substrates for the active site- therefore the inhibitor is diluted out
Why does K Apparent Increase?
An inhibitor slows or stops the enzymative process therefore Vo is slow and it takes more [S] to get to 1/s of the Vmax- As more and more inhibiotr is added- the steeper the line gets thereforeless substrate is needed to get to half of vmax (look at graph)
what is Ki?
Inhibition constant
What does a low Ki mean for potency?
Lower ki is more potent INHIBITOR
What does a high Ki mean for potency?
Less potent inhibitor
What is an example of a Competive inhibitor? Why?
Malanate competetively inhibits Succinate because of its similar structioe
What does K cat tell you?
how fast an enzyme can go when its compelety saturated with substrate aka its the Vo value of Vmax's point on the graph
How do you determine the location of vmax?
multiply Km by 10= vmax
Equation for Kcat
Kcat=Vmax/Et where Et=total concentration of enzymes
What part of the equilibrium equation is Kcat enzymes?
In the **ES**--> E + P part bc Kcat measures how fast ES complex breaks down (aka turn over)
What units are associated with Kcat? what do these tell you
min-1 or sec -1- tells you the number of moles of S converted to P/ unity of time divided by the moles of E
What does it mean when ACh estrace has a high Kcat?
it breaks down ACh very fast and has a high turn over
What ist he second ex of comeptitve inhibition?
Iondol inhibiting Chymotrypsin
How are trp from peptide chain and Indole similar in the way they look?
The TRP of the peptide chain has a R group that IS indole
What is the cause when indole binds in chymotrypsins active site?
The peptide can't bind and be hydrolyzed (REMEMBER: chymotrypsin cleaves at Trp )
Wat is the third example of competitive inhibitor? (Make lots of money)
Zocor and Lipitor (-statin drugs) for the inhibition of HMG-COa
What do zocor and lipitor inhibit?
HMG-COa
What does HMG-COa do?
enzyme for biosynthesis of cholesterol
How do non competitive inhibitors differ from competitive?
DO NOT bind at active site or resemle substrate
Fxn of Non competitive inhibitors?
Interfere with enzyme- do NOT affect binding of enzyme
Frequency of non competitive inhibitors in drugs?
Not common- don't know where going to bind so hard to design
Describ the line weaver burke plot for Non Competitive inhibitors?
Km is Constant, (1/vmax) increases and Vmax decreases
Analogy Whitman used for NCI?
Sticking stick in bike wheel
What are ex of NCI drugs? What is inhibited?
Treating Aids- inhibits reverse transcriptase