KNES 464 Lecture Notes - Lecture 9: Non-Competitive Inhibition, Enzyme Kinetics, Enzyme

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maroonarmadillo314

5 Nov 2018

School

University of Maryland

Department

Kinesiology

Course

KNES 464

Professor

Dr. Sarah Kuzmiak-Glancy

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Lecture 9

V max- on y axis

- Relationship between substrate and rate of reaction

- Plateaus at V max

- Km (units of substrate concentration)

o Substrate concentration at which the ½ V max occurs

Enzyme kinetics

- Sensitivity

- If Km were to steep lower, then line would be steeper

o Small change in substrate concentration results in a larger velocity change at any

given concentration

o The steeper the line, the more sensitive—a small change on x axis would give a

bigger change in y axis

Enzymes and Inhibitors

- If you have WAYYYY more enzymes than substrate, then none of the following would

happen

- If change enzyme concentration (add more), then V max is increased, but no change in

o Km is a property of the enzyme—the km relates to the enzyme, but can increase

V max

- Competitive Inhibitor

o Looks very close to the substrate

o Will go into binding site of the enzyme and block the way for the substrate

(physical barrier)

o Can add so much substrate and kick the inhibitor out

▪ Will affect the km because it will take longer to get to the V max, because

▪ Raise km, because less sensitive

- Noncompetitive Inhibitor

o Will change the enzyme- sometimes it makes it so that the substrate can’t bind

or sometimes it makes it so that the substrate binds, but cannot undergo the

activity of the enzyme

o Binds far from the binding site- do not bind at binding site

o Therefore, V max is affected (lower because less place for them to go)

▪ If have noncompetitive inhibitor, it will be on that enzyme no matter how

much enzyme

▪ Substrate cannot outcompete the enzyme becayse it is not there

▪ Km does not change

o Sensitivity is the same but V max is lower

V max

More Enzyme

Increase

No change

Competitive Inhibitor

No change

higher

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Document Summary

Relationship between substrate and rate of reaction. Km (units of substrate concentration: substrate concentration at which the v max occurs. If you have wayyyy more enzymes than substrate, then none of the following would happen. If change enzyme concentration (add more), then v max is increased, but no change in km: km is a property of the enzyme the km relates to the enzyme, but can increase. If have noncompetitive inhibitor, it will be on that enzyme no matter how much enzyme: substrate cannot outcompete the enzyme becayse it is not there, km does not change, sensitivity is the same but v max is lower. Amount of energy required or released required by the reaction is a function of how far it is from equilibrium. At equilibrium- gibbs free energy is 0: no net movement. Mass action ratio: ratio of concentration of product over the concentration(s) of reactant(s, r= [b]/[a, atp adp + pi, r= [adp] x [pi]/ [atp]

Related Questions

Ignore the circled answers, some of them are wrong but I don't know which. What are the correct answers for questions 1-5?

Which of the following is not correct concerning the action of enzymes 1. a. An enzyme lowers the Energy of the products and thus makes the reaction more favorable. A 1:1 Enzyme substrate complex (ES) must be formed before the enzyme can convert the substrate to product. e3 An enzyme speeds up both the forward reaction and the reverse reaction. d. Enzymes ean are stereoselective because the active site is 3-Dimensional and preferentially binds one enantiomer over the other. e. A mutational change of any residue in the active site ofan enzyme has a significant effect on the activity of the enzyme. Procaine Hydrochloride is a local anesthetic often used by dentists. The structure shown to the right represents procaine in the active site of the enzyme procaine esterase. Consider this substrate in the active site of the enzyme to answer the next three questions. Assume pH 7. 2. What type of residue might be located as a binding (recognition) residue at location #2? a. A polar noncharged residue that can form a Hydrogen bond. b. A negatively charged residue that can form an ion-ion interaction (salt bridge). c. A nonpolar residue that can be favorably involved in a hydrophobic interaction. A positively charged residue that can form a salt bridge. ea Any type of residue since there is no significant feature on the substrate to bind to. 3. Which of the following might be a likely binding residue at location #3? Asp residue a. Lys residue b. Ala residue e) he residue c. Met residue 4. Which of the following amino acid residue side chains would never be a catalytic residue in the active site of an enzyme? Glutamic acid a. Serine Histidine Phenylalanine b. c. Cysteine 5. Which of the following is correct conceming Michaelis Menten kinetics for enzyme catalyzed reactions? a. The V max is obtained when [S] is equal to 2 KM b. KM is equal to V occurs the when the enzyme is saturated with substrate The kinetic plot of velocity vs. [S] is linear. e. A useful approximation is "The larger the KM, the better the Eto S binding."

1. You have the following prokaryotic DNA sequence: 5â²-GGACTAGACAATAGGGACCTAGAGATTCCGAAA-3â² 3â²-CCTGATCTGTTATCCCTGGATCTCTAAGGCTTT-5â² If the top strand is the template strand which sequence below is the correct mRNA transcript? A. 5â²-GGACUAGACAAUAGGGACCUAGAGAUUCCGAAAâ3â² B. 5'-UUUCGGAAUCUCUAGGUCCCUAUUGUCUAGUCC-3' C. 5'-CCUGAUCUGUUAUCCCUGGAUCUCUAAGGCUUU-3' D. None of the above are correct

2.Starting in the cytoplasm with a fully mature mRNA explain the process of translation initiation and then elongation and termination to me.

3.Prior to export from the nucleus, pre-mRNA must be processed. What specifically does this entail?

4.The biosynthetic pathway for the two amino acids E and H is shown schematically in the figure. You are able to show experimentally that E inhibits enzyme V, and H inhibits enzyme X. The most logical hypothesis regarding the regulation of Enzyme T would be that it is most likely subject to feedback inhibition by E alone. True or False?

5. A. kinase B. ligase C. polymerase D. oxido-reductase E. Phosphatase F. protease G. nuclease H. ATPase 1. Removes a phosphate group from a molecule 2. Hydrolyzes ATP 3. Hydrolyzes bonds between nucleotides 4. Adds phosphate groups to molecules 5. Catalyzes reactions in which one molecule is oxidized and another is reduced 6. Hydrolyzes peptide bonds 7. Joins two ends of DNA together 8. Catalyzes the synthesis of polymers such as RNA and DNA

6. Looking at the figure showing the change in reaction rate for two different enzymes that both utilize the same substrate, answer the following questions. a. What is the approximate Vmax for enzyme B ? b. What is the approximate Vmax for enzyme A ? c. What is the approximate Km for the enzyme which has a higher affinity for the substrate uM.

7. Answer the following question either yes or no (spell out the word, do not abbreviate as y or n). Looking at the following coupled reaction: Luciferase luciferin + O 2 ==========> oxyluciferin + light âG = + + Mg2+ ATP <=> AMP + PPi âG = - - - a. Based on your knowledge of free energy change and reactions would this coupled reaction occur ? b. Would changing the second step from ATP<=> AMP + PPi âG = - - - to ATP <=> ADP + Pi âG = - change your answer

7.Spontaneous reactions by definition will happen instantaneously. Why false?

8. Each of the following questions apply to the image of the channel protein. The purple sphere is a charged ion. Type your response to each question in the blank provided. a. Based you on what you know about cells and ions, what does the tri-lobed red and white molecule represent (although there aren't anywhere near enough of them shown) ? b. Since the question stated the purple sphere was a charged particle, using what you know about the tri-lobed red and white molecule what is the charge of the purples sphere c. On the extracellular space, on the right side of the purple sphere, there are two tri-lobed red and white molecules in close proximity to one another. The red of one appears to be attracted to the white of the other. What type of bond is this ? d. Based on your knowledge of proteins that interact with the membrane and the properties of the membrane, to what family of amino acids would the amino acid marked by A. most likely belong? ?

KNES 464 Lecture Notes - Lecture 9: Non-Competitive Inhibition, Enzyme Kinetics, Enzyme

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