Concept explainers
(a)
Interpretation:
The order of elution of aspartate before serine by
Concept introduction:
Ion-exchange chromatography is used to separate mixture of amino acids on the basis of their overall charge by using cation or anion-exchange resins.
Dowex-50 is a cation-exchange resins with less polar used for Cation-exchange chromatography.
Cation-exchange chromatography separate amino acids according to their
(b)
Interpretation:
The order of elution of serine before alanine by
Concept introduction:
Ion-exchange chromatography is used to separate mixture of amino acids on the basis of their overall charge by using cation or anion-exchange resins.
Dowex-50 is a cation-exchange resins with less polar used for Cation-exchange chromatography.
Cation-exchange chromatography separate amino acids according to their
(c)
Interpretation:
The order of elution of valine before leucine by
Concept introduction:
Ion-exchange chromatography is used to separate mixture of amino acids on the basis of their overall charge by using cation or anion-exchange resins.
Dowex-50 is a cation-exchange resins with less polar used for Cation-exchange chromatography.
Cation-exchange chromatography separate amino acids according to their
(d)
Interpretation:
The order of elution of tyrosine before phenylalanine by
Concept introduction:
Ion-exchange chromatography is used to separate mixture of amino acids on the basis of their overall charge by using cation or anion-exchange resins.
Dowex-50 is a cation-exchange resins with less polar used for Cation-exchange chromatography.
Cation-exchange chromatography separate amino acids according to their
Want to see the full answer?
Check out a sample textbook solutionChapter 17 Solutions
Essential Organic Chemistry, Global Edition
- The -helical parts of myoglobin and other proteins stop whenever a proline residue is encountered in the chain. Why is proline never present in a protein helix?arrow_forward3. Draw the tripeptide Alanine-Cysteine-Serine (R1 = CH3, R2 = CH2SH, R3 = CH2OH) under the following pH conditions and list the net charge on the protein. A. pH= 1 Net charge? B. pH=7 Net charge? C. pH=12 Net charge?arrow_forwardAll amino acids have two ionizable functional groups: an α‑amino group (average pKa of 9.4) and an α‑carboxylic acid group (average pKa of 2.2). Aspartic acid has an ionizable side chain (R group) with a pKa of about 3.8. One of the possible ionization states of aspartic acid is shown in the image. At what pH would the structure be the predominant ionization state? Consider the ionization state of all three of the functional groups.arrow_forward
- Could someone explain what this is saying? I would like a better understanding. FIGURE D CPP32 (Caspase-3) protease activity. Aliquots of cell lysates (50μL) were incubated with an equal volume (50 μL) of the reactionbuffer and 5 μL of 7-amino-4-trifluoromethyl coumarin (AFCDEVD) for 1 hour at 37˚C (Clontech). The shift in fluorescenceemission of AFC-DEVD, on its proteolysis to free AFC by theprotease, was detected in a fluorometer, using a 400 nm excitationfilter and 505 nm emission filter.arrow_forwardThe isoelectric point (pl) can best be calculated by: Averaging the sums of all pkas. Averaging the sum of the two pKas closest to physiological pH. Averaging the two pKas "sandwiching" the zwitterionic form. Averaging the two pKas of the alpha-amino and alpha-carboxy groups.arrow_forward29.Which amino acid is ideal for the transfer of protons within the catalytic site of enzymes due to the presence of significant amount of both the protonated and deprotonated forms of its side chain at biological pH? A. Lysine B. Asparagine C. Tyrosine D. Cysteine E. Histidine 30. The isoelectric point of alanine is pH = 6.15. It is mixed with proline (pka1 = 2.0; pka2 = 10.6). The mixture is placed in an electric field at pH 6.15 and then subjected to isoelectric focusing. Which statement is true? A. The two amino acids will be separated B. The two amino acids will not be separated C. Neither amino acids will move in the electric field D. Both amino acids will move from the origin and separatedarrow_forward
- Isoelectric focusing can separate peptides based on their relative contents of acidic and basic residues. When voltage is applied to an electrophoretic gel with Amino acid pK Arg 12.5 a pH gradient, each peptide migrates until it reaches a point where it has no net charge. The pH at this point is the isoelectric point (pl) for that peptide. Asp 3.7 Cys 8.2 One can estimate the pl fairly accurately (within 0.1 or 0.2 pH units) using the Glu 4.3 pK values of all the proton dissociable groups in the peptide. His 6.0 Consider the hexapeptide Met-Asp-Lys-Arg-Ala-Tyr. Lys 10.5 Tyr 10.5 *peptide-NH; 8.0 *peptide-COOH 3.4 * Amino and carboxy terminal values differ from the a amino and carboxy values of a single amino acid. Step 1: Determine the total positive charge on the hexapeptide when all acidic and basic groups are fully charge: protonated. Enter your answer without the sign.arrow_forwardOrnithine is an amino acid that is not used in the synthesis of proteins, but is an important intermediate in several metabloic pathways including the urea cycle and the synthesis of polyamines. It has a perfectly ordinary terminal amino group and terminal carboxyl group like any other amino acid (so use the pKas for those groups given on your amino acids handout), and a side chain with a single ionizable side group with a pKa of 10.3. If ornithine is placed in solution at pH 7.0, it has a net charge of +1. What would the net charge on this amino acid be if the pH of the solution was raised to pH 12.0? Please explain your reasoning.arrow_forwardWhich of the following amino acid cannot bind a heme group using its side chain as an axial ligand? A. Lysine B. Valine C. Histidine D. Cystinearrow_forward
- Amino Acids and Proteins 1. What are the structural features of amino acids with an emphasis on essential amino acids? 2. Write the properties of amino acids: zwitterion, pka, pKb, amphoteric character, isoelectric point, and electrophoresis. 3. Write the mechanism of peptide bond formation and what are its structural features. 4. What are the different types of proteins and their function? 5. Explain the meaning and importance of the primary, secondary, tertiary, and quaternary structures of a protein and the factors that cause its denaturation.arrow_forwardWhat is the charge of each amino acid residue in the peptide chain and what is the net charge on the whole protein at pH = 4 (Use the provided table)? KGL pka Value Alpha Carboxy |+Alpha Amino Side Chain Amino Acid Name Glycine Alanine Valine 2.34 9.60 2.34 9.69 2.32 9.62 Leucine 2.36 9.60 Non-Polar Amino Acids Isoleucine Methionine Phenylalanine Tryptophan 2.36 9.68 2.28 9.21 1.83 9.13 2.38 9.39 Proline 1.99 10.60 Serine Threonine Cysteine Tyrosine Asparagine Glutamine 2.21 9.15 2.63 9.10 1.71 10.78 8.33 Polar Amino Acids 2.2 9.11 10.07 2.02 8.84 2.17 9.13 Aspartic Acid Glutamic Acid Lysine Arginine 2.09 9.82 3.86 Acidic Amino Acids 2.19 9.67 4.25 2.18 8.95 10.79 Basic Amino acids 2.17 9.04 12.48 Histidine 1.82 9.17 6.04arrow_forward10. Use the information in the table below to draw the structure of the predominant form of each amino acid at physiological pH (pH = 7.4) R side chain pKa (a-COOH) -CH₂CH(CH3)2 -(CH2)4NH2 -(CH2)2CO2H Amino acid Leucine Lysine Glutamic acid L-leucine L-lysine L-glutamic acid 2.36 2.18 2.19 pKa (α-NH3*) pKa (side chain) 9.60 8.95 9.67 10.79 4.25arrow_forward
- Introduction to General, Organic and BiochemistryChemistryISBN:9781285869759Author:Frederick A. Bettelheim, William H. Brown, Mary K. Campbell, Shawn O. Farrell, Omar TorresPublisher:Cengage LearningChemistry: Principles and ReactionsChemistryISBN:9781305079373Author:William L. Masterton, Cecile N. HurleyPublisher:Cengage Learning
- Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning