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-Gln-Phe Val-Leu-Gly-Met-Ser-Arg Cyanogen bromide treatment Gln-Phe Val-Leu-Gly-Met lle-Lys-Gly-Tyr-Met Ser-Arg-Asn-Thr-Trp-Met

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-Gln-Phe Val-Leu-Gly-Met-Ser-Arg Cyanogen bromide treatment Gln-Phe Val-Leu-Gly-Met lle-Lys-Gly-Tyr-Met Ser-Arg-Asn-Thr-Trp-Met

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter26: Biomolecules: Amino Acids, Peptides, And Proteins

Section26.SE: Something Extra

Problem 57AP: Oxytocin, a nonapeptide hormone secreted by the pituitary gland, functions by stimulating uterine...

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Oxytocin, a nonapeptide hormone secreted by the pituitary gland, functions by stimulating uterine contraction and lactation during childbirth. Its sequence was determined from the following evidence: 1. Oxytocin is a cyclic compound containing a disulfide bridge between two cysteine residues. 2. When the disulfide bridge is reduced, oxytocin has the constitution Asn, Cys2, Gln, Gly, Ile, Leu, Pro, Tyr. 3. Partial hydrolysis of reduced oxytocin yields seven fragments: Asp-Cys, Ile-Glu, Cys-Tyr, Leu-Gly, Tyr-Ile-Glu, Glu-Asp-Cys, and Cys-Pro-Leu. 4. Gly is the C-terminal group. 5. Both Glu and Asp are present as their side-chain amides (Gln and Asn) rather than as free side-chain acids. What is the amino acid sequence of reduced oxytocin? What is the structure of oxytocin itself?
What is the structure of a nonapeptide that gives the following fragments when cleaved? Trypsin cleavage: Val-Val-Pro-Tyr-Leu-Arg, Ser-Ile-Arg Chymotrypsin cleavage: Leu-Arg, Ser-Ile-Arg-Val-Val-Pro-Tyr
A sample of an unknown peptide was divided into two aliquots. One aliquot was treated with trypsin; the other one 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-Ile-Lys Gly-Tyr-Met-Gln-Phe Val-Leu-Gly-Met-Ser-Arg Cyanogen bromide treatment Gln-Phe Val-Leu-Gly-Met Ile-Lys-Gly-Tyr-Met
A peptide has the following amino acid composition: 2 Met, 2 Phe, 2 Glu, 1 Arg, 1 Lys, 1 Val, 1 Leu, 1 Gly, 1 Ser Reaction of the intact peptide with dansyl chloride followed by acid hydrolysis creates a derivative of Met. A specific cleavage of the intact peptide produces fragments with the following sequences: Fragment A: Glu-Gly-Lys-Phe Fragment B: Met-Ser-Leu-Arg Fragment C: Met-Val-Glu-Phe What information do this result give about the sequence of the peptide? Explain how you arrived on your answer. a) The sequence is: Met-Val-Glu-Phe-Glu-Gly-Lys-Phe-Met-Ser-Leu-Arg b) The sequence is: Met-Ser-Leu-Arg-Met-Val-Glu-Phe-Glu-Gly-Lys-Phe c) The sequence is: Met-Val-Glu-Phe-Met-Ser-Leu-Arg-Glu-Gly-Lys-Phe d) The sequence is: Met-Ser-Leu-Arg-Glu-Gly-Lys-Phe-Met Val-Glu-Phe
Determine 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
Determine 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, Met
Determine 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
Determine 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-Phe
Three peptides were obtained from a trypsin digestion of two different polypeptides. In each case, indicate the possible sequences from the given data and tell what further experiment should be carried out in order to determine the primary structure of the polypeptide. a. polypeptide I: 1. Val-Gly-Asp-Lys 2. Leu-Glu-Pro-Ala-Arg 3. Ala-Leu-Gly-Asp b. polypeptide II: 1. Val-Leu-Gly-Glu 2. Ala-Glu-Pro-Arg 3. Ala-Met-Gly-Lys
What products are formed when below mentioned peptide is treated with trypsin. Phe–Tyr–Gly–Cys–Arg–Ser
Determine 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, Ser
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.