(a)
To determine: The mechanism for the reaction of the N terminus of the peptide with 2,4-dinitrofluorobenzene.
Interpretation: The mechanism for the reaction of the N terminus of the peptide with 2,4-dinitrofluorobenzene is to be determined.
Concept introduction: The process in which a proper series of amino acids is maintained in the peptide chain is known as edmann degradation. this process includes the labelling of terminal amino residue followed by the cleavage of this terminal amino residue from the peptide chain. the peptide bonds between other amino acids do not get disturb during this process.
(b)
To determine: The reason that the Edman degradation is usually preferred over the Sanger method.
Interpretation: The reason that the Edman degradation is usually preferred over the Sanger method is to be determined.
Concept introduction: The process in which a proper series of amino acids is maintained in the peptide chain is known as edmann degradation. this process includes the labelling of terminal amino residue followed by the cleavage of this terminal amino residue from the peptide chain. the peptide bonds between other amino acids do not get disturb during this process.
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EP ORGANIC CHEMISTRY -MOD.MASTERING 18W
- Deduce the sequence of a heptapeptide that contains the amino acids Ala, Arg, Glu, Gly, Leu, Phe, and Ser, from the following experimental data. Edman degradation cleaves Leu from the heptapeptide, and carboxypeptidase forms Glu and a hexapeptide. Treatment of the heptapeptide with chymotrypsin forms a hexapeptide and a single amino acid. Treatment of the heptapeptide with trypsin forms a pentapeptide and a dipeptide. Partial hydrolysis forms Glu, Leu, Phe, and the tripeptides Gly-Ala-Ser and Ala-Ser-Arg.arrow_forwardWhich of the following reagents is used to protect the amino group of the N-terminal residue in solution-phase peptide synthesis? 單選: O a. trifluoroacetic acid O b. benzyl chloroformate O c. dicyclohexylcarbodiimide O d. phenyl isothiocyanate O e. lithium diisopropyl amidearrow_forwardReaction of a polypeptide with carboxypeptidase A releases Met. The polypeptide undergoes partial hydrolysis to give the following peptides. What is the sequence of the polypeptide? 1. Ser, Lys, Trp 4. Leu, Glu, Ser 7. Glu, His 10. Glu, His, Val 2. Gly, His, Ala 5. Met, Ala, Gly 8. Leu, Lys, Trp 11. Trp, Leu, Glu 3. Glu, Val, Ser 6. Ser, Lys, Val 9. Lys, Ser 12. Ala, Metarrow_forward
- Deduce the sequence of a heptapeptide that contains the amino acids Ala, Arg, Glu, Gly, Leu, Phe, and Ser, from the following experimental data. Edman degradation cleaves Leu from the heptapeptide, and carboxypeptidase forms Glu and a hexapeptide. Treatment of the heptapeptide with chymotrypsin forms a hexapeptide and a single amino acid. Treatment of the heptapeptide with trypsin forms a pentapeptide and a dipeptide. Partial hydrolysis forms Glu, Leu, Phe, and the tripeptides Gly–Ala–Ser and Ala–Ser–Arg.arrow_forwardA. Write the structure of the pentapeptide GLDSC. B. What is the complete name of this pentapeptide? Show a tertiary structure of ACGGC after a disulfide bond forms. A sample of an unknown peptide was divided into two aliquots. One aliquot was treated with trypsin; the other was treated with cyanogen bromide. Given the following sequences (N-terminal to C- terminal) of the resulting fragments, deduce the sequence of the original peptide. Trypsin treatment Asn-Thr-Trp-Met-lle-Lys Gly-Tyr-Met-Gin-Phe Val-Leu-Gly-Met-Ser-Arg Cyanogen bromide treatment Gin-Phe Val-Leu-Gly-Met lle-Lys-Gly-Tyr-Met Ser-Arg-Asn-Thr-Trp-Metarrow_forwardYou may use the following table of pKa values for typical amino acid substituents. alpha carboxylate group Sidechain carboxylate Imidazole alpha amino group Guanidino group First [Select] 2 [Select] 4 Thiol sidechain amino group Consider the following 3 peptides. Last 6 9 12 8 Peptide 1: E-H-A-D-E-K Peptide 2: E-D-R-H-Y-G Peptide 3: G-E-G-D-S-D What would be the order of elution of these peptides for a anion exchange column at pH 7.0? 11 [Select]arrow_forward
- On the paper provided, draw the chemical structure of a peptide with a sequence YIQV at pH 14. The pKa value of the Y sidechain is 10.1.arrow_forwardIn a paragraph form provide the experimental procedure of the reaction of oxazetidine-containing peptides and α-ketoacid that will result in protein that contain native serine residuesarrow_forwardThrough acid hydrolysis for 24 hours, Jackson obtained the following amino acid residues: Ala-Arg-Cys-Gln-Lys-Phe-Tyr-Val No phenylthiohydantoin structure was obtained after Edman analysis. Furthermore, no C-terminal residue was also obtained after treatment with carboxypeptidase. He then used trypsin and chymotrypsin enzymes as cleaving agents. Trypsin cleaves at the C-terminal of basic amino acids Lys and Arg while chymotrypsin cleaves at the C-terminal of aromatic amino acids such as Phe, Tyr, and Trp. The results of trypsin and chymotrypsin cleavage were listed in the table below: Enzyme Amino Acid Residues Chymotrypsin Trypsin Determine the sequence of the polypeptide using the one-letter code of the amino acids. Kindly check the lecture slide for the amino acid one-letter codes. Drag the correct boxes to their respective markers. The directionality of the N-to-C terminals is also specified below. N-terminal Val-Lys-Ala-Phe + Gln-Arg-Cys-Tyr Cys-Tyr-Val-Lys + Ala-Phe-Gln-Arg I…arrow_forward
- A normal polypeptide and a mutant of the polypeptide were hydrolyzed by an endopeptidase under the same conditions. The normal and mutant poly peptide differ by one amino acid. The fingerprints of the peptides obtained from the two polypeptides are shown below. What kind of amino acid substitution occurred as a result of the mutation? (That is, is the substituted amino acid more or less polar than the original amino acid? Is its pI lower or higher?)arrow_forwardDraw the structure of the tetrapeptide Asp-Arg-Val-Tyr. Please show the appropriate stereochemistry of the natural amino acids in the resulting peptide. Please draw all ionizable groups in their neutral form.arrow_forwardSomatostatin is a tetradecapeptide of the hypothalamus that inhibits the release of pituitary growth hormone. Its amino acid sequence has been determined by a combination of Edman degradations and enzymic hydrolysis experiments. On the basis of the following data, deduce the primary structure of somatostatin: 1. Edman degradation gave PTH-Ala. 2. Selective hydrolysis gave peptides having the following indicated sequences: Phe-Trp Thr-Ser-Cys Lys-Thr-Phe Thr-Phe-Thr-Ser-Cys Asn-Phe-Phe-Trp-Lys Ala-Gly-Cys-Lys-Asn-Phe 3. Somatostatin has a disulfide bridge.arrow_forward