(a)
Interpretation:
The peptides obtained from the cleavage of given peptide chain by carboxypeptidase A has to be given.
Concept introduction:
Amino acids are linked each other by peptide bonds is called protein (one or more peptide bonds). Peptide bonds are amide bonds, in which carbonyl group of one amino acid bonded to amino group of other amino acid. The chain of the protein is drawn in such a way that left end is occupied by free amino group (say N-terminal) and right side of the chain is occupied by carbonyl group (say C-terminal).
Exopeptidases cleave peptide bonds that are not at the end.
Carboxypeptidase A is an exopeptidase, which cleave the peptide bond of C-terminal amino acid except arginine and lysine.
(b)
Interpretation:
The peptides obtained from the cleavage of given peptide chain by cyanogen bromide has to be given
Concept introduction:
Amino acids are linked each other by peptide bonds is called protein (one or more peptide bonds). Peptide bonds are amide bonds, in which carbonyl group of one amino acid bonded to amino group of other amino acid. The chain of the protein is drawn in such a way that left end is occupied by free amino group (say N-terminal) and right side of the chain is occupied by carbonyl group (say C-terminal).
Cyanogen bromide cleaves the C-terminal peptide of Methionine in a peptide chain.
(c)
Interpretation:
The peptides obtained from the cleavage of given peptide chain by trypsin has to be given.
Concept introduction:
Amino acids are linked each other by peptide bonds is called protein (one or more peptide bonds). Peptide bonds are amide bonds, in which carbonyl group of one amino acid bonded to amino group of other amino acid. The chain of the protein is drawn in such a way that left end is occupied by free amino group (say N-terminal) and right side of the chain is occupied by carbonyl group (say C-terminal).
Endopeptidases cleave peptide bonds that are not at the end.
Trypsin is an endopeptidase, which cleave the C-side peptide bond of positively charged side chains such as arginine and lysine.
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Chapter 17 Solutions
Essential Organic Chemistry (3rd Edition)
- An unknown decapeptide was isolated and characterized. Complete hydrolysis of this peptide gave : F(2), A,G,C,K,N,T, W and V. Treatment with carboxypeptidase releases A. Reaction with Edman’s reagent gave PTH-T and a nonapeptide. The nonapeptide was treated with trypsin and gave 2 peptides: (V-C-G-A) and (N-FF-W-K). Give the sequence of amino acid in the decapeptide.arrow_forwardBradykinin is a linear nonapeptide released by blood plasma globulin in response to a wasp sting. It is a very potent pain-causing agent. Its constituent amino acids are 2R, G, 2F, 3P, S. The sue of 2,4-dinitrofluorobenzene and carboxypeptidase shows that both terminal residues are arginine. Partial hydrolysis of bradykinin gives the following di- and tripeptides: FS + PGF +PP + SPF + FR + RParrow_forwardWrite out the steps needed to synthesize the following peptide using the Merrifield method.arrow_forward
- Determine 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_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_forwardA nonapeptide released by globulins in the blood in response to a waspsting. Hydrolysis gives the following amino acids: 2 Arg, Gly, 2 Phe, 3 Pro, and Ser.Edman degradation gives phenylthiohydantoin of Arg. Cleavage with carboxypeptidase gives Arg. Partial hydrolysis gives the following di- and tripeptides: Phe-Ser, Pro-GlyPhe, Pro-Pro, Ser-Pro-Phe, Phe-Arg, and Arg-Pro. What is the amino acid sequence of this peptide?arrow_forward
- Given the following peptide SEPIMAPVEYPK(a) Estimate the net charge at pH 7 and at pH 12. Assume the pKa valuesgiven in as shown. (b) How many peptides would result if this peptide were treated with(1) cyanogen bromide, (2) trypsin, or (3) chymotrypsin?(c) Suggest a method for separating the peptides produced by chymotrypsintreatment.arrow_forwardA tripeptide on hydrolysis produced glycine, alanine and leucine. The structures of these amino acids are shown below. On reaction with Edman’s reagent, leucine was released as the phenylhydantoin. Treatment of the tripeptide with carboxypeptidase gave glycine. Draw the structure of the tripeptide.arrow_forwardGiven the following peptideSEPIMAPVEYPK(a) Estimate the net charge at pH 7 and at pH 12. Assume the pKa valuesgiven in Table (b) How many peptides would result if this peptide were treated with(1) cyanogen bromide, (2) trypsin, or (3) chymotrypsin?(c) Suggest a method for separating the peptides produced by chymotrypsintreatment.arrow_forward
- Leuprolide is a synthetic nonapeptide used to treat both endometriosis in women and prostate cancer in men. (a) Both C-terminal and N-terminal amino acids in leuprolide have been structurally modified. Identify the modifications. (b) One of the nine amino acids in leuprolide has d stereochemistry rather than the usual L. Which one? (c) Write the structure of leuprolide using both one- and three-letter abbreviations. (d) What charge would you expect leuprolide to have at neutral pH?arrow_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.Treatment with cyanogen bromide gives three peptides with the following amino acid compositions:1. His, Lys, Met, Pro, Ser 2. Thr, Val 3. Ala, Arg, Leu, Lys, Met, Serarrow_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. Treatment with cyanogen bromide gives three peptides with the following amino acid compositions: 1. His, Lys, Met, Pro, Ser 2. Thr, Val 3. Ala, Arg, Leu, Lys, Met, Ser Trypsin-catalyzed hydrolysis gives three peptides and a single amino acid: 1. Arg, Leu, Ser 2. Met, Pro, Ser, Thr, Val 3. Lys 4. Ala, His, Lys, Metarrow_forward
