Concept explainers
Interpretation:
A structure for the octapeptide is to be proposed from the following observations. a) It shows the composition Asp, Gly2, Leu, Phe, Pro2, Val on amino acid analysis. b) Edmund analysis showed Glycine as the N-terminal group and Leucine as the C-terminal group. C) The following fragments are produced during acidic hydrolysis Val-Pro-Leu, Gly, Gly-Asp-Phe-Pro, Phe-Pro-Val.
Concept introduction:
The aminoacid sequence of a peptide can be arrived by arranging the fragments produced during hydrolysis in a line one below the other such that N-terminal amino acid is at the left and C-terminal acid at the right and identifying the overlapping amino acids.
To propose:
A structure for the octapeptide which shows the reactions given.
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Chapter 26 Solutions
Organic Chemistry
- Give the amino acid sequence of hexapeptides that produce the following sets of fragments upon partial acid hydrolysis: (a) Arg, Gly, Ile, Leu, Pro, Val gives Pro-Leu-Gly, Arg-Pro, Gly-Ile-Val (a) N, L, M, W, V2 gives V-L, V-M-W, W-N-Varrow_forwardDetermine the primary structure of an octapeptide from the following data: Acid-catalyzed hydrolysis gives 2 Arg, Leu, Lys, Met, Phe, Ser, and Tyr. Carboxypeptidase A releases Ser. Edman’s reagent releases Leu. Treatment with cyanogen bromide forms two peptides with the following amino acid compositions: 1. Arg, Phe, Ser 2. Arg, Leu, Lys, Met, Tyr Trypsin-catalyzed hydrolysis forms the following two amino acids and two peptides: 1. Arg 2. Ser 3. Arg, Met, Phe 4. Leu, Lys, Tyrarrow_forwarddecapeptide has the following amino acid composition:Ala2 , Arg, Cys, Glu, Gly, Leu, Lys, Phe, ValPartial hydrolysis yields the following tripeptides:Cys-Glu-Leu + Gly-Arg-Cys + Leu-Ala-Ala+ Lys-Val-Phe + Val-Phe-Gly.Reaction of the decapeptide with 2,4-dinitrofluorobenzene yields 2,4-dinitrophenylysine. From the experimental data, deduce the primary structure of the decapeptide.(b) Suggest a scheme you will follow to synthesize the dipeptide Ala-Gly.arrow_forward
- Using the information below, determine the amino acid sequence of the peptide, and explain how your structure is consistent with each piece of information. Complete hydrolysis by 6 M HCl at 110°C followed by amino acid analysis indicated the presence of Gly, Leu, Phe, and Tyr in a 2:1:1:1 molar ratio. Treatment of the peptide with1-fluoro-2,4-dinitrobenzene followed by complete hydrolysis and chromatography indicated the presence of the 2,4-dinitrophenyl derivative of tyrosine. No free tyrosine could be found. Complete digestion of he peptide with pepsin (which cleaves on the amino side of aromatic residues) followed by chromatography yielded a dipeptide containing Phe and Leu and a tripeptide containing Tyr and Gly in a 1:2 ratio.arrow_forwardDetermine the amino acid sequence of a polypeptide from the following data: Complete hydrolysis of the peptide yields Ala, Arg, Gly, 2 Lys, Met, Phe, Pro, 2 Ser, Tyr, and Val. Treatment with Edman’s reagent releases PTH-Val. Carboxypeptidase A releases Ala. Treatment with cyanogen bromide yields the following two peptides: 1. Ala, 2 Lys, Phe, Pro, Ser, Tyr 2. Arg, Gly, Met, Ser, Val Treatment with trypsin yields the following three peptides: 1. Gly, Lys, Met, Tyr 2. Ala, Lys, Phe, Pro, Ser 3. Arg, Ser, Val Treatment with chymotrypsin yields the following three peptides: 1. 2 Lys, Phe, Pro 2. Arg, Gly, Met, Ser, Tyr, Val 3. Ala, Serarrow_forwardAn 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.arrow_forward
- 1. A decapeptide has the following amino acid composition:Ala2 , Arg, Cys, Glu, Gly, Leu, Lys, Phe, ValPartial hydrolysis yields the following tripeptides:Cys-Glu-Leu + Gly-Arg-Cys + Leu-Ala-Ala+ Lys-Val-Phe + Val-Phe-Gly.Reaction of the decapeptide with 2,4-dinitrofluorobenzene yields 2,4-dinitrophenylysine. a.From the experimental data, deduce the primary structure of the decapeptide.b.Suggest a scheme you will follow to synthesize the dipeptide Ala-Glyarrow_forwardDetermine the amino acid sequence of a polypeptide from the following data:Acid-catalyzed hydrolysis gives Ala, Arg, His, 2 Lys, Leu, 2 Met, Pro, 2 Ser, Thr, and Val.Carboxypeptidase A releases Val.Edman’s reagent releases PTH-Leu.Trypsin-catalyzed hydrolysis gives three peptides and a single amino acid:1. Arg, Leu, Ser 3. Lys2. Met, Pro, Ser, Thr, Val 4. Ala, His, Lys, Metarrow_forwardA chemically modified guanidino group is present in cimetidine (Tagamet), a widely prescribed drug for the control of gastric acidity and peptic ulcers. Cimetidine reduces gastric acid secretion by inhibiting the interaction of histamine with gastric H, recep- tors. In the development of this drug, a cyano group was added to the substituted gua- nidino group to alter its basicity. Do you expect this modified guanidino group to be more basic or less basic than the guanidino group of arginine? Explain. N-CN H,C CH,SCH,CH,NHËNHCH, HN, Cimetidine (Tagamet)arrow_forward
- Select the correct representation of this aminoacid in aqueous solution at the stated pH values. pKa (a-CO₂H) = 2.20 pK₂ (α-NH₂) = 9.11 pKa (side chain OH) = 10.07 pl = 5.63 HO Lont out on on OH OH NH₂ NH₂ NH₁ HO NH₂ B D at pH 1 HO NH₂ of of an OH NH₂ NH₂ NH3 O E F G at pH 9.59 at pH 13. at pH 5.63 (the isoelectric point) HO OH HO [Choose ] [Choose ] [Choose ] [Choose ] an NH3 H OHarrow_forwardDetermine the amino acid sequence of a polypeptide from the following data: Complete hydrolysis of the peptide yields Arg, 2 Gly, Ile, 3 Leu, 2 Lys, 2 Met, 2 Phe, Pro, Ser, 2 Tyr, and Val. Treatment with Edman’s reagent releases PTH-Gly. Carboxypeptidase A releases Phe. Treatment with cyanogen bromide yields the following three peptides: 1. Gly-Leu-Tyr-Phe-Lys-Ser-Met 2. Gly-Leu-Tyr-Lys-Val-Ile-Arg-Met 3. Leu-Pro-Phe Treatment with trypsin yields the following four peptides: 1. Gly-Leu-Tyr-Phe-Lys 3. Val-Ile-Arg 2. Ser-Met-Gly-Leu-Tyr-Lys 4. Met-Leu-Pro-Phearrow_forwardDetermine the amino acid sequence of a polypeptide from the following data:Complete hydrolysis of the peptide yields Arg, 2 Gly, Ile, 3 Leu, 2 Lys, 2 Met, 2 Phe, Pro, Ser, 2 Tyr, and Val.Treatment with Edman’s reagent releases PTH-Gly.Carboxypeptidase A releases Phe. Treatment with cyanogen bromide yields the following three peptides:1. Gly-Leu-Tyr-Phe-Lys-Ser-Met 2. Gly-Leu-Tyr-Lys-Val-Ile-Arg-Met 3. Leu-Pro-Phearrow_forward