On the mass spectrum given in Supplemental Sheet 1, the 'y7' and the 'yg'ions, both carrying one positive charge and differing by one amino acid residue,are shown as having peaks at m/z = 880.46 and m/z = 979.49, respectively.(i) Explain using appropriate chemical equations what is meant by a 'y' ion.(ii)The y7 and y8 ions differ by one amino acid. Identify this amino acid residuefrom the following three possibilities. Show all your workings.Average Molecular WeightAmino AcidAlanineValineSerine(g mol-¹)89.09117.15105.09

Solution:(i)1) Consider a peptide or protein molecule with the following general structure:…

Answered: On the mass spectrum given in…

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter3: Stereoisomerism And Chirality

Section3.8: The Significance Of Chirality In The Biological World

Problem DQ

See similar textbooks

Similar questions

Para-aminobenzoic acid has two ionizable groups. One is a carboxylic acid that ionizes through loss of a proton thereby forming a charged para-aminobenzoic acid carboxylate anion, and the other is an amine connected to an aromatic (benzene) ring that ionizes by accepting an H+ to form a positively charged ammonium ion. The pk of the carboxylic acid is 4.9 and the pk of the amino group is 2.5. Assume that the intracellular pH within a bacterial cell is 7.0. N- H O-H H + H-N- H pK₂ = 2.5 Which of the following structures correctly depicts how most of the para-aminobenzoic acid is ionized at pH 7? A. B. O-H C. H H + H-N- H H D. H N- O-H H pK₂ = 4.9
2) Part of the 'H NMR spectrum for a dipeptide recorded in D₂O is shown below. The signal for the CH 3 group is not shown. (i) Explain what has happened to the H-atoms attached to the N atoms. (ii) Interpret the spectrum Note the signals for HA and HA are subject to a second order effect. 'N- HAHA' 40 Hz H 0.1 ppm L-Ala-Gly
8. You are using mass spectrometry to determine the molecular weight of a peptide, which has multiple peaks (each represents an M/Z value) during the detection. You obtain M/Z values of 305 and 609 for two of these peaks. What is the molecular weight of the peptide: 152 153 b. 305 d. 608 1217
The electrospray ionization mass spectrum of the tripeptide Ala-Met-Thr shows peaks of mono-protonation and di-protonation of the tripeptide. At what values of m/z would these peals be expected? Briefly explain and show your workings.
What are two ways to measure the total amount of all proteins in a purification sample? O 1) Calculating the yield and 2) calculating the purity of a purification. O 1) Measuring absorbance at 280 nm and 2) using an enzymatic assay for your protein of interest. O 1) Quantitating the amount of your protein of interest using binding of a labeled antibody (e.g.. an ELISA) and 2) using a dye-binding assay. O 1) Measuring absorbance at 280 nm and 2) using a dye-binding assay.
Q1)In the pH range 1.82 to 8.99, H2Arg+ is the principal form of arginine. Which is the second most prominent species at pH 6.0? At pH 5.0?Q2) (a) Draw the structure of the predominant form (principal species) of 1,3-dihydroxybenzene at pH 9.00 and at pH 11.00.(b) What is the second most prominent species at each pH?(c) Calculate the percentage in the major form at each pH
About a decade ago, it was more common to use peptide mass mapping to identify a protein cut from a gel. Peptide mass mapping involves digesting the protein with trypsin and then measuring the peptide masses using MALDI-TOF mass spectrometry. The more superior method of identifying a protein from a gel is to digest the protein with trypsin and then use liquid chromatography to separate the peptides. The separated peptides are then electrosprayed into a tandem mass spectrometer. The MS-MS data is uploaded into a database such as MASCOT for protein identification. Explain why the LC-MS-MS method is superior to the peptide mass mapping method.
3) The chemical structure for an asparagine residue in a peptide is given below. NH₂ ZI 'N' H NH 8.75 ppm, NH₂ 7.59, 6.91 ppm, СßH 2.83, 2.75 ppm, CaH 4.75 ppm (i) (ii) (iii) (iv) Draw out a 1-D ¹H NMR spectrum for this residue include the multiplicity of each signal. For simplicity in your drawing take that the coupling constant for the NH-CH >> CH-CH. Show the approx. relative height of the signals and clearly assign each peak in the spectrum. Draw out a 1H-1H COSY spectrum for this residue. Clearly assign each diagonal peak and show all the cross peaks in the spectrum. How many spin systems are in the residue? Draw in the extra peaks that would occur in the ¹H-¹H TOCSY spectrum for this residue
The 1H NMR for a dipeptide recorded in D20 is shown below. (i) Explain what has happened to the H- atoms attached to the N atoms. (ii) Explain the spectra. Note the signals for HA and HA'are subject to a second order effect. H^H* 40 Hz 0.1 ppm 'N- DN Ha L-Ala-Gly (iii) predict which direction the signal for the H on the alpha-C will move in the 1H NMR on going from low to high ph and explain why this leads to a change in chemical shift.
Shown below is a section of beta-sheet from the protein thioredoxin. Amide nitrogens are indicated by circled Ns, carbonyl oxygens by Os, and hydrogen bonds by gray lines. M strand 1 MO strand 3 (N) O 1 2 3 4 For each strand of the sheet (1, 2, 3, 4) indicate the direction (top or bottom) of the N-terminus. [Select] strand 2 [Select] O [Select] strand 4 [Select] strands 1 and 2 Determine the orientation (parallel or antiparallel) of each adjacent strand to one another. [ Select] AHO strands 2 and 3 [Select] N strands 3 and 4 [Select] >
An amino acid mixture of phenylalanine, glycine and glutamic acid is to be separated bypaper chromatography. The solvent is less polar than water. Which of these amino acids will have the highest Rf value and which the lowest? Explain. Treatment of a new protein with dansyl chloride reveals two (2) dansyl-labelled derivatives of amino acids, alanine and methionine. What can you deduce about the structure of the protein from these results? Name the amino acids that contribute atoms to both purine and pyrimidine rings.
1) The zwitterionic form of leucine has a structure H3C CH 3 H NH₂+ H H H (i) Draw out the structure at pH 1 (ii) Draw out the structure at pH 12 (iii) -COO- Predict which direction the signal for the H on on the α C will move in the ¹H NMR on going from low to high pH. (iv) Explain why this change in chemical shift occurs.

SEE MORE QUESTIONS

Recommended textbooks for you

Organic Chemistry

Chemistry

ISBN:

9781305580350

Author:

William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:

Cengage Learning

Organic Chemistry

Chemistry

ISBN:

9781305080485

Author:

John E. McMurry

Publisher:

Cengage Learning

Organic Chemistry

Chemistry

ISBN:

9781305580350

Author:

William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:

Cengage Learning

Organic Chemistry

Chemistry

ISBN:

9781305080485

Author:

John E. McMurry

Publisher:

Cengage Learning

SEE MORE TEXTBOOKS