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_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_forwardNonearrow_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_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_forward1. 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_forward
- 2arrow_forwardGlycine is a diprotic acid, which can potentially undergo two dissociation reactions, one for the a-amino group (-NH3), and the other for the carboxyl (-COOH) group. Therefore, it has two pKą values. The carboxyl group has a pK₁ of 2.34 and the a-amino group has a pK₂ of 9.60. Glycine can exist in fully deprotonated (NH₂-CH₂-COO-), fully protonated (NH3-CH₂-COOH), or zwitterionic form (NH3-CH₂-COO-). Match the pH values with the corresponding form of glycine that would be present in the highest concentration in a solution of th pH. fully deprotonated form NH,−CH,−COO- pH 11.9 pH 6.0 pH 8.0 fully protonated form NH3-CH₂-COOH pH 1.0 Answer Bank pH 7.0 zwitterionic form NH3-CH₂-COO-arrow_forwardPlease don't provide handwritten solution ......arrow_forward
- Calculate the pl of arginine. Give your answer to two decimal places. pI =arrow_forwardAnother method to form a peptide bond involves a two-step process Conversion of a Boc-protected amino acid to a p-nitrophenyl ester. Why does a p-nitrophenyl ester “activate” the carboxy group of thefirst amino acid to amide formation?arrow_forwardTreatment of a polypeptide with 2-mercaptoethanol yields two polypeptides with the following primary structures: Val-Met-Tyr-Ala-Cys-Ser-Phe-Ala-Glu-Ser Ser-Cys-Phe-Lys-Cys-Trp-Lys-Tyr-Cys-Phe-Arg-Cys-Ser Treatment of the original intact polypeptide with chymotrypsin yields the following peptides: 1. Ala, Glu, Ser 3. Tyr, Val, Met 5. Ser, Phe, 2 Cys, Lys, Ala, Trp 2. 2 Phe, 2 Cys, Ser 4. Arg, Ser, Cys 6 Tyr, Lys Determine the positions of the disulfide bridges in the original polypeptide.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage LearningIntroduction to General, Organic and BiochemistryChemistryISBN:9781285869759Author:Frederick A. Bettelheim, William H. Brown, Mary K. Campbell, Shawn O. Farrell, Omar TorresPublisher:Cengage Learning