2. Amino acid analysis of the a heptapeptide gave the following residues: Asp Glu Leu Lys Met Tyr Trp NH4+. The following facts were observed: Trypsin treatment had no effect. The phenylthiohydantoin released by Edman degradation was OH H C-C-CH₂ H. Brief chymotrypsin treatment yielded several products including a dipeptide and a tetrapeptide. The tetrapeptide contained Glu, Leu, Lys and Met is some order. Cyanogen bromide treatment afforded a tetrapeptide that had a net positive charge at pH 7 and tripeptide that had a zero net charge at pH 7. What is the amino acid sequence for this heptapeptide?

2. Amino acid analysis of the a heptapeptide gave the following residues: Asp Glu Leu Lys Met Tyr Trp NH4+. The following facts were observed: Trypsin treatment had no effect. The phenylthiohydantoin released by Edman degradation was OH H C-C-CH₂ H. Brief chymotrypsin treatment yielded several products including a dipeptide and a tetrapeptide. The tetrapeptide contained Glu, Leu, Lys and Met is some order. Cyanogen bromide treatment afforded a tetrapeptide that had a net positive charge at pH 7 and tripeptide that had a zero net charge at pH 7. What is the amino acid sequence for this heptapeptide?

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter6: Energy, Enzymes, And Biological Reactions

Section: Chapter Questions

Problem 8TYK: Which of the following statements about the allosteric site is true? a. The allosteric site is a...

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6 (a) A decapeptide has the following amino acid composition: Ala2 , Arg, Cys, Glu, Gly, Leu, Lys, Phe, Val Partial 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
1. A certain polypeptide was treated with trypsin and yielded the following Fragments: Leu-Glu Gly-Tyr-Asn-Arg Gln-Ala-Phe-Val-Lys The same polypeptide was treated with chymotrypsin and yielded the following fragments: Gln-Ala-Phe Asn-Arg-Leu-Glu Val-Lys-Gly-Tyr What is the amino acid sequence of this polypeptide? Instructions Make use of the table below to determine the sequence of the mystery protein.
2. A group of peptides that influence nerve transmission in certain parts of the brain have been isolated from normal brain tissue. These peptides are known as opioids. Using the information below, determine the amino acid sequence of this particular opioid: ● Complete hydrolysis by HCl at 100° C followed by amino acid hydrolysis analysis indicated the presence of Gly, Leu, Phe, and Tyr, in a 2:1:1:1 ratio. ● Treatment of the peptide with FNDB followed by complete hydrolysis indicated the presence of 2,2-dinitrophenyl derivative of tyrosine. No free tyrosine could be found. ● Complete digestion of the peptide with chymotrypsin yielded free tyrosine and leucine, plus a tripeptide containing Phe and Gly in a 1:2 ratio. Instructions Make use of the table below to determine the sequence of the mystery protein:
1. What is the isoelectric point (pI) of lysine which has pKa values of 2.1 for the α carboxyl group, 9.7 for the α amino group and 10.5 for the side chain amino group? 2. Which of the following is most likely to be found on the exterior of a protein? A) Pro B) Trp C) Ser D) Glu 3. The type of reaction that forms a peptide bond is A) Elimination B) Hydrolysis C) Nucleophilic substitution D) Condensation
1 Draw the following polypeptide: Met- Tyr-Val-Ser-Asn 2A Draw the hydrolysis of a dipeptide consisting of phenylaline and glutamic acid. 2B What are the fuctional group present in the side chains of the amino acids.( phenylalanine and glutamic acid) 2C are the sidechains in part 2B hydrophobic or polar 2D where would you expect to find them ( surface or interior of a protein) ? why ?
8. Match each of the following amino acids with the intermediate needed for its synthesis.(a) 3-Phosphoglycerate 1. glutamate 2. serine 3. asparagine (b) oxaloacetate 1. glutamate 2. serine 3. Asparagine
Treatment of a polypeptide with 2-mercaptoethanol yields two polypeptides 1. Ile—Val—Cys—Arg—Thr—Gly—Cys—Lys—Asn—Phe—Leu2. Trp—Lys—Cys—Phe—Arg—His—Thr—Lys—Cys—SerTreatment of the intact polypeptide with trypsin yields fragments with the following aminoacid compositions(Arg, Cys2, Ile, Ser, Val)(Arg, Cys2, Gly, Lys, Thr, Phe)(Asn, Leu, Phe)(His, Lys, Thr)(Lys, Trp)Edmands chemistry reveal the following PTH derivatives in equal quantity after cycle 1• PTH--Ile and PTH--Trp a) Rewrite the intact polypeptide, by indicating the positions of the disulfide bonds(Indicate your reasoning) b) How many products do you expect after chymotrypsin cleavage of the intactpolypeptide? c) You are performing an isoelectric focusing experiment (IEF) on a gel with a pH range of 2to 14. Indicate on the diagram below at what point along the gel will peptide 1 abovefocus, in the presence (X) and absence (Y) of DTT. (also show your calculations)
2 Please draw the arrow-pushing mechanism to create the polyketide backbone chain of TYLOSIN. If two or more extension rounds are exactly the same, you do not need to draw them more than once. However, please clearly indicate which steps are being repeated. Please draw the complete “business end” of any cofactors you use in a step
9. At pH ___, the pentapeptide Ala-Glu-His-Val-Cys would contain two positively charged groups and one negatively charged group. a) 9 b) 3 c) 7 d) 1 e) 5
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1. Draw three-dimensional representations of the following amino acids. Explain theirstructures.(a) L-phenylalanine(b) L-histidine(c) D-serine(d) L-tryptophan
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