Uracil and Adenine are two nitrogen bases constitutive of RNA. Both compoundsshow maximum absorption spectra at 260 nm. A 20 µmol.L-¹ uracil solution gives anabsorbance value of 0.24 at 260 nm (in a 1 cm-optical path length cuvette).1- Calculate the molar extinction coefficient of uracil at 260 nm.2- A solution containing a mixture of unknown concentrations of adenine and uracilshows an absorbance value at 260 nm of 0.4 (1 cm-optical path length cuvette).Considering that the molar concentration of uracil is twice the one of adenine, andthat the molar extinction coefficient of adenine at 260 nm is 16000 mol¹.L.cm-¹,calculate the molar concentrations of adenine and uracil in the mixture.-1

The Beer Lamberts equation relates the absorbance value given by an analyte for a particular…

Answered: Uracil and Adenine are two nitrogen…

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

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Protein concentration can readily be determined using the Beer-Lambert law: A = e l c where A = absorbance e = molar absorption coefficient (M-1cm-1) l = light path length (cm) c = concentration (M) If the molar absorption coefficient at 280 nm for yeast ADH is 48860 M-1cm-1 and a 10 mL solution of the protein has an absorbance at 280 nm of 0.4 (as measured by a spectrometer with pathlength 1 cm), then what is the concentration of the protein solution (in μM)? i.e. concentration = ______ μM If the molecular weight of the protein is 36849, what is its concentration in mg/mL? i.e. concentration = _______ mg/mL For each part of the question, show your calculations to arrive at your answers.
1)Ubiquitin is a small protein with a monoisotopic mass of 8560 Da. a) Electrospray ionization of this small protein typically results in major charge states of +8, +9, +10, +11, +12, and +13. Using this information, complete the table below, assuming the charges on each come from protonation. Report mass and m/z values to the ones place. b) Using the data you entered in the table, sketch an expected ESI-MS spectrum for ubiquitin. Label each peak with its charge state. What do you notice about the spacing of peaks along the x-axis. c)The figure shows an experimentally obtained electrospray mass spectrum for ubiquitin. Compare this spectrum to the spectrum you predicted. Are there any differences? If so, what might cause these differences?
6 Concanavalin (ConA) is a 25.5KDa protein with pI of 4.7 and optical absorbance (A 0.1% 289) of 1.14. calculate the concentration of an aqueous solution of pure BSA protein with an absorbance of 0.66 at 280nm. give your answer in units of mg/ml ?
Calculate the net charge on the following tripeptides at pH 5.0: (a) Leu-His-Asp [0] (b) Ala-Ile-Val [0] (c) Met-Lys-Arg [+2] (d) Which tripeptide will be retained the shortest on a cation-exchange chromatographic column in a pH 5.0 buffer? Why?
Diethylaminoethyl cellulose is a positively charged resin used in ion-exchange chromatography with a pKa is about 11. A negatively charged protein with an isoelectric point of 5.0 is applied to the column in a buffer at pH 7 and containing 0.1 M NaCl. Which of the following conditions is most likely to weaken the interaction between the protein and the resin? A Raising the pH to 8 and decreasing the NaCl to 0.05 M B Raising the pH to 8 and increasing the NaCl to 0.2 M C Lowering the pH to 6 and decreasing the NaCl to 0.05 M D Lowering the pH to 6 and increasing the NaCl to 0.2 M
calculate the volume of stock solutions required to make up the buffer solutions that will be used for protein purification. The solutions you need to prepare for purification are: i. Binding Solution A: make up 50 mL 50 mM HEPES buffer (pH 7.5), 300 mM NaCl, 5mM imidazole, 5% (v/v) glycerol ii. Wash Solution B: make up 50 mL 50 mM HEPES buffer (pH 7.5), 300 mM NaCl, 75mM imidazole, 5% (v/v) glycerol iii. Elution Solution C: make up 10 mL 50 mM HEPES buffer (pH 7.5), 300 mM NaCl, 500 mM imidazole, 5% (v/v) glycerol please show your working . Thnk you
You are given a pure protein sample to characterize and provided the following information: Its molar extinction coefficient, ε280, is 0.25 liters micromole-1 cm-1 in both the folded and unfolded form Its ΔGo for unfolding is 1.5 kcal/mol at 37o (where RT = 0.59 kcal/mole) A) Using a 0.5 cm pathlength cell, you measure the absorbance at 280 nm of a 20-fold dilution of your pure protein in solution (by this, we mean that 50 ul of the protein sample was diluted to a final volume of 1 ml) and find A280 = 0.40. What is the original concentration of the protein before dilution? B) What is the concentration of the unfolded form of the protein in your sample?
Nonspecific elution of affinity bonded macromolecules is used in affinity chromatography explain why?
Consider the following properties of the protein components of a sample mixture as provided in the table below: 1. if the mixture is subjected to gel filtration chromotography which protein component elute first? 2. if the mixture is subjected to isoelectric focusing which protein will stop m oving nearest to the positive electrode? 3. if the mixture is subjected to cation-exchange chromotography using a buffer at ph 7 which protein will bind to the resin? 4.if the mixture is subjected to SDS-PAGE which protein will be at bottomost portion of gel? 5.if the mixture is subjected to hydrophobic interaction chromotography which protein will bind most strongly to the resin?
You want to treat 10 mL of HL-60 cells with cycloheximide in order to determine the half-life of a newly discovered protein. In order to do this, the final concentration of cycloheximide needs to be 90 µM. How much of a 150 mM stock solution of cycloheximide should you add to your cells?
Ferritin is treated with SDS or SDS and b-mercaptoethanol and subjected to polyacrylamide gel electrophoresis. Only when very large amounts of bisacrylamide are added do you see two separate bands on the gel at relative migrations of 4.0245 and 3.9375 and the results are the same with and without b-mercaptoethanol. You decide to call these the light and heavy chains of ferritin. What are the actual sizes of the light and heavy chains of ferritin based on the SDS-PAGE data? What types of interactions hold these proteins together in the structure of ferritin?
a. An oligopeptide ALVGALGATPTPQMWSHSWRGVSIKS was digested with trypsin.Which method would be most appropriate for separating the products: ion exchange or gel filtration chromatography? Explain.b. Suppose that the peptide was digested with cyanogen bromide. What would be the optimal separation technique? Explain

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