a.b.C.Sphingosine-1-phosphate (SPP) has recently been discovered to be important for cell survival. Thesynthesis of SPP form sphingosine and ATP is catalyzed by the enzyme sphingosine kinase. Anunderstanding of the kinetics of the sphingosine kinase reaction may be important in the developmentof drugs to treat cancer. The velocity of the sphingosine kinase reaction was measured in the presence(5 µM) and absence of threo-sphingosine, a stereoisomer of sphingosine. The results are shown below.The sphingosine kinase used in all the reactions was 10 mg.Sphingosine (uM)2.53.55102050vo (mg. min-¹)(no inhibitor)32.34050.87287.7115.4What are the KM and V MAX in the presence and absence of the inhibitor?What kind of an inhibitor is threo-sphingosine? What is the K₁ value?What is the Keat (turn over number)?vo (mg. min-¹)(with threo-sphingosine)7.610.514.625.443.970.8

For a one-substrate enzyme-catalyzed reaction, the Michaelis-Menton equation shows the quantitative…

Answered: Sphingosine-1-phosphate (SPP) has…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter18: Glycolysis

Section: Chapter Questions

Problem 17P

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If intracellular [ATP] = 5 mM, [ADP] = 0.5 mM, and [Pi] = 1.0 mM, calculate the concentration of AMP at pH 7 and 25°C under the condition that the adenylate kinase reaction is at equilibrium.
Explain the role and functioning of chaperone proteins. Explain, why several chaperones (chaperonins) possess an ATPase activity?
There is an enzyme that catalyzes the production of the pigment responsible for dark fur color in Siamese cats and Himalayan rabbits. This enzyme is thermolabile, meaning that it does not function at higher temperatures. Rabbits raised at 5°C are all black. If raised at 20°C, they are white with black paws, ears, and noses; they are all white when raised at 35°C. Draw an activity curve for this enzyme, and explain.
4. a. Calculate the KM (Michaelis constant) and the vmax (the maximum initial rate) for both substrates (sphingosine and ATP). Show your work, and be careful about units. b. threo-dihydrosphingosine, a stereoisomer of sphingosine, is an inhibitor of sphingosine kinase. What kind of inhibitor (competitive, uncompetitive, noncompetitive) is threo-dihydrosphingosine? Citing information from the Lineweaver-Burke plots, explain how you can tell.
Sphingosine-1-phosphate (S1P) is important for cell survival. The synthesis of S1P from sphingosine and ATP is catalyzed by the enzyme sphingosine kinase. An understanding of the kinetics of the sphingosine kinase reaction may be important in the development of drugs to treat cancer. The velocity of the sphingosine kinase reaction was measured in the presence and absence of threo-sphingosine, a stereoisomer of sphingosine that inhibits the enzyme. The results are shown below. Construct a Lineweaver-Burk plot to answer the following questions: (a) What are the apparent KM and Vmax values in the presence and absence of the inhibitor? (b) What kind of an inhibitor is threo-sphingosine? Explain.
Sphingosine-1-phosphate (S1P) is important for cell survival. The synthesis of S1P from sphingosine and ATP is catalyzed by the enzyme sphingosine kinase. An understanding of the kinetics of the sphingosine kinase reaction may be important in the development of drugs to treat cancer. The velocity of the sphingosine kinase reaction was measured in the presence and absence of threo-sphingosine, a stereoisomer of sphingosine that inhibits the enzyme. The results are shown below. Construct a Lineweaver–Burk plot to answer the following questions: (a) What are the apparent KM and Vmax values in the presence and absence of the inhibitor? (b) What kind of an inhibitor is threo-sphingosine? Explain.
Sphingosine 1-phosphate (SPP) is important for cell survival. The synthesis of SPP from sphingosine and ATP is catalyzed by the enzyme sphingosine kinase. An understanding of the kinetics of the sphingosine kinase reaction may be important in the development of drugs to treat cancer. The velocity of the sphingosine kinase reaction was measured in the presence and absence of threo-sphingosine, a stereoisomer of sphingosine that inhibits the enzyme. The results are shown below .[Sphingosine], μM 2.5 3.5 5 10 20 50 v0(mg·minꟷ1) no inhibitor 32.3 40 50.872 87.7 115.4 v0(mg·minꟷ1)with threo-sphingosine 8.5 11.5 14.6 25.4 43.9 70.8 Construct a Lineweaver-Burk plot to answer the following questions:(A)What are the apparent KMand Vmaxvalues in the presence and absence of the inhibitor?(B)What kind of inhibitor is threo-sphingosine? Explain this type of inhibition.
In a Lineweaver-Burk graph, the lines representing the uninhibited and inhibited enzyme catalyzed reaction meet each other on the x-axis. The type of inhibition which is occurring is: a) competitive b) noncompetitive c) uncompetitive d) allosteric CO2 exerts direct activity upon hemoglobin by: a) blocking oxygen from binding to the heme group b) displacing BPG from the central cavity c) oxidizing Fe+2 to Fe+3 which does not bind oxygen d) forming an N-terminal carbamate which favors the T-state The dominant motif found in hemoglobin and myoglobin is: a) helix-turn-helix b) twisted beta sheet c) beta barrel d) random coil Which of these is an ketohexose? a) fructose b) glucose c) ribose d) erythrose Which of these is a constitutional isomer of d-glucose? a) fructose b) galactose c) l-glucose d) ribose Which of these is an enantiomer of d-glucose? a) d-fructose b) d- galactose c) l-glucose d) d-ribose Which of these is a diastereomer of…
A.What is the Result of the sodium potassium ATPase activity in the cell? B.What mechanism does the sodium potassium ATPase use to achieve this result? C. Why is the above-mentioned change in affinity critical for the sodium potassium ATPase to perform its function?
Inhibitors of acetylcholinesterase, such as edrophonium, are used to treat Alzheimer’s disease. The substrate for acetylcholinesterase is acetylcholine. Structures are attached. What kind of inhibitor is edrophonium? Explain. Can inhibition by edrophonium be overcome in vitro by increasing the substrate concentration? Explain. Does this inhibitor bind reversibly or irreversibly to the enzyme? Explain.
A point mutation in Hb diminishes hydrophobicity at the heme. Which of the following impacts would you predict? . Increased oxidation of Fe2+ and loss of O2 binding b. Decreased negative charges needed at the dimer/dimer interface to stabilize the T-state c. Decreased positive charges needed at the dimer/dimer interface to stabilize the T-state d. Shift the O2 binding curve of Hb to the left e. Decreased affinity for BPG in the T-state
The phosphorylation and oxidative decarboxylation of oxaloacetate by inorganic phosphate (Pi) to make phosphoenolpyruvate and carbon dioxide is endergonic under intracellular conditions. It is characterized by this equation: Oxaloacetate + Pi ←→ Phosphoenolpyruvate + H2O + CO2 ΔG’ = +24.6 kJ/mol The synthesis of GTP from GDP and inorganic phosphate (Pi) in solution is endergonic under intracellular conditions, and it is characterized by this equation: GDP + Pi ←→ GTP + H2O ΔG’ = +30.5 kJ/mol Write a new net thermodynamically coupled reaction equation that describes the synthesis of phosphoenolpyruvate from oxaloacetate using the hydrolysis of GTP to power the reaction and calculate the new net ΔG’ of this reaction. Show all of your work.

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