### Enzyme Kinetics of Sphingosine KinaseSphingosine-1-phosphate (SPP) has recently been discovered to be 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 (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.#### Kinetic Data Table:| Sphingosine (μM) | v₀ (mg·min⁻¹) (no inhibitor) | v₀ (mg·min⁻¹) (with **threo-sphingosine**) ||------------------|-----------------------------|-----------------------------------------|| 2.5 | 32.3 | 7.6 || 3.5 | 40 | 10.5 || 5 | 50.8 | 14.6 || 10 | 72 | 25.4 || 20 | 87.7 | 43.9 || 50 | 115.4 | 70.8 |#### Analytical Questions:1. **What are the KM and VMAX in the presence and absence of the inhibitor?** - To determine the KM and VMAX, Michaelis-Menten plots or Lineweaver-Burk plots of the data would be used.2. **What kind of an inhibitor is threo-sphingosine? What is the KI value?** - Identify whether threo-sphingosine is a competitive, noncompetitive, or uncompetitive inhibitor by analyzing the impact on KM and VMAX. - KI value can be calculated using inhibitor kinetics equations.3. **What is the Kcat (turn over number)?** - The K<

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

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

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

The active site of an enzyme that uses a general acid-base catalytic mechanism contains a Glu and an Asp residue (both of which are essential for catalysis) with pKa values of 5.9 and 4.5, respectively. If the enzyme is found in the lysosome (pH = 5.2), which residue will act as the general acid and which will act as the general base during the initial steps of the reaction?
The first order decomposition of cyclobutane, C4H8 is shown below: C4H8(g) 2 C2H4(g) The value of the rate constant is 9.20 x 10-3 s-1 at 500°C. Initially, 100.0 kg of C4H8 is present in a container. How long will it take for 80.0 kg of C4Hg to decompose?
With the help of the half reactions given in Table 1, formulate the redox equation for the oxidation of succinate and reduction of ubiquinone.
About the process of industrial production of ethanol by the yeast Saccharomyces cerevisiae, mark the correct alternatives: (a) the cells must be cultured in anaerobic conditions to activate the metabolic pathway of ethanol production (b). the presence of oxygen is required to allow regeneration of the NAD+ cofactor (c). good oxygenation of the medium is important to favor the formation of greater amounts of ATP (d).the production of ethanol is always accompanied by the formation of glycerol (e). the sugar present in the culture medium is completely oxidized to CO2 and water
A particular enzyme-catalyzed reaction has an apparent Vmax = 9.00 nmol s-1 and α' = 3.00 when 2.00 µmol L-1 inhibitor X is present and uncompetitively inhibiting the reaction. Calculate Vmax for the uninhibited reaction in nmol s-1.
Methyl-labeled [14C]methionine at a specific activity of 2.0 millicuries per millimole was injected into rats. Six hours later the rats were killed. Phosphatidylcholine was isolated from the liver and found to have a specific activity of 1.5 millicuries per millimole. Calculate the proportions of phosphatidylcholine synthesized by the phosphatidylserine pathway and by the pathway starting from free choline. What further information would you need for your calculated values to reflect the true rates of these processes?
One of your colleagues has obtained a sample of muscle phosphorylase b that is known to be relatively inactive. She has approached you for advice on how to set up an appropriate assay. She has the following items available, not all of which are appropriate for this study. Help her out by selecting the items that she should use and what their purpose is in the assay, and then explain why each of the other items would not be useful. 1. 100 UM AMP 2. 100 UM GTP 3.100 uM glucose 4. 100 uM glucose 6-phosphate 5. Branched glycogen 6. Amylose (i.e. unbranched glycogen) 7.50 mM HEPES buffer, pH 7.5 8. 50 mM potassium phosphate buffer, pH 7.5 Write out a short explanation for each of the above items, and upload your answers by the due date.
Many enzymes obey simple Michaelis–Mentenkinetics, which are summarized by the equationrate = Vmax [S]/([S] + Km)where Vmax = maximum velocity, [S] = concentration ofsubstrate, and Km = the Michaelis constant.It is instructive to plug a few values of [S] into theequation to see how rate is affected. What are the rates for[S] equal to zero, equal to Km, and equal to infinite concen-tration?
Consumption of nitrate-rich vegetables such as spinach have been shown to reduce blood pressure in prehypertensive individuals (i.e., those having no history of clinical hypertension), a phenomenon attributed to increased nitric oxide synthesis. Describe the reactions that convert nitrate (NO3 −) to nitric oxide (NO•) in the body.
The toxic effect of Na+ ions can be avoided in some plant species by storing them in membrane-bound vacuoles within the cytosol. Calculate the maximum vacuolar-to-cytosolic [Na+] ratio that could be achieved by a Na+/H+ antiport mechanism in the vacuolar membrane if the cytosolic pH is 7.4 and the vacuolar pH is 5.6.
Allosteric inhibitors of hemoglobin will decrease enzyme activity (oxygen binding) through which of the following mechanisms? Binding the enzyme in "T" conformation and displacing an activator Binding the enzyme and enhancing the Vmax Binding the enzyme, and keeping it in the "R" conformation Binding the enzyme, and keeping it in the "T" conformation
In a major metabolic pathway involving the monosaccharide glucose, one of the reactions involve the conversion of glucose to glucose-6-phosphate summarized below together with accompanying free energy change: glucose + phosphate = glucose-6-phosphate + H,0 AG = 13.8 kJ · mol-1 (Reaction 1) In cells, the production of G6P (Reaction 1 above) is coupled to a reaction that involves the hydrolysis of ATP to ADP (shown below, Reaction 2) which makes the overall reaction much more favorable to the production of glucose-6-phosphate. ATP + H,O = ADP + phosphate (Reaction 2) Why do you think coupling the production of glucose-6-phosphate to the hydrolysis of ATP makes the overall reaction spontaneous? What can you say about the free energy change accompanying the hydrolysis of ATP (Reaction 2)?

SEE MORE QUESTIONS

Recommended textbooks for you

Biochemistry

ISBN:

9781319114671

Author:

Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:

W. H. Freeman

Lehninger Principles of Biochemistry

Biochemistry

ISBN:

9781464126116

Author:

David L. Nelson, Michael M. Cox

Publisher:

W. H. Freeman

Fundamentals of Biochemistry: Life at the Molecul…

Biochemistry

ISBN:

9781118918401

Author:

Donald Voet, Judith G. Voet, Charlotte W. Pratt

Publisher:

WILEY

Biochemistry

ISBN:

9781319114671

Author:

Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:

W. H. Freeman

Lehninger Principles of Biochemistry

Biochemistry

ISBN:

9781464126116

Author:

David L. Nelson, Michael M. Cox

Publisher:

W. H. Freeman

Fundamentals of Biochemistry: Life at the Molecul…

Biochemistry

ISBN:

9781118918401

Author:

Donald Voet, Judith G. Voet, Charlotte W. Pratt

Publisher:

WILEY

Biochemistry

ISBN:

9781305961135

Author:

Mary K. Campbell, Shawn O. Farrell, Owen M. McDougal

Publisher:

Cengage Learning

Biochemistry

ISBN:

9781305577206

Author:

Reginald H. Garrett, Charles M. Grisham

Publisher:

Cengage Learning

Fundamentals of General, Organic, and Biological …

Biochemistry

ISBN:

9780134015187

Author:

John E. McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. Peterson

Publisher:

PEARSON

SEE MORE TEXTBOOKS