I. Analysis of a peptide antibiotic purified from a strain of Bacillus brevii resulted in the following significant information: Complete hydrolysis of the peptide yielded equimolar amounts of Leu, Orn, Phe, Pro, and Val Molecular weight of the peptide was estimated to be aroung 1,200 Da The peptide failed to undergo hydrolysis when treated with carboxypeptidase Partial hydrolysis and then chromatographic separation of products yielded the following di- and tripeptides: Leu-Phe, Phe-Pro, Orn-Leu, Val-Orn, Val-Orn-Leu, Phe-Pro-Val, Pro-Val-Orn

I. Analysis of a peptide antibiotic purified from a strain of Bacillus brevii resulted in the following significant information: Complete hydrolysis of the peptide yielded equimolar amounts of Leu, Orn, Phe, Pro, and Val Molecular weight of the peptide was estimated to be aroung 1,200 Da The peptide failed to undergo hydrolysis when treated with carboxypeptidase Partial hydrolysis and then chromatographic separation of products yielded the following di- and tripeptides: Leu-Phe, Phe-Pro, Orn-Leu, Val-Orn, Val-Orn-Leu, Phe-Pro-Val, Pro-Val-Orn

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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1. Analysis of a peptide antibiotic purified from a strain of Bacillus brevii resulted in the following significant information: - Complete hydrolysis of the peptide yielded equimolar amounts of Leu, Orn, Phe, Pro, and Val - Molecular weight of the peptide was estimated to be aroung 1,200 Da - The peptide failed to undergo hydrolysis when treated with carboxypeptidase - Partial hydrolysis and then chromatographic separation of products yielded the following di- and tripeptides: Leu-Phe, Phe-Pro, Orn-Leu, Val-Orn, Val-Orn-Leu, Phe-Pro-Val, Pro-Val- - Orn Treament with dinitrofluorobenzene (DNFB) followed by complete hydrolysis yielded only free amino acids and the DNFB-derivatized ornithine at its side chain By using the above information, deduce the amino acid sequence of this peptide antibiotic. Write the final peptide sequence using 3-letter abbreviations. Show the complete and step by step solution.
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:
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
pls explain why Which of these CANNOT BE achieved using SDS-PAGE?I. Estimate the MW of a protein.II. Confirm the identity of a protein.III. Confirm the presence of quaternary structure in the protein.IV. Give a qualitative assessment of the protein extract purity.V. Determine the shape of the protein.a. II and Vb. III and IVc. I, III and Vd. I, II, and IV Which of the following statements are TRUE about the discontinuous gel in SDSPAGE?I. The sandwich effect occurs because of the lower mobility of the zwitterionic form of glycine compared to the protein band in the stacking gel.II. Because of the larger pores in the resolving gel, proteins move faster in the stacking gel, but decelerate at the boundary of the two gels.III. In the stacking gel, in terms of net negative charge of the species, the order is: zwitterionic glycine > proteins > chloride ion.IV. The higher pH in the resolving gel allows glycine to carry a more negative charge, resulting in higher mobilities compared to…
Explain amino acids being amphoteric electrolytes to form peptidebonds. State at least 5 general limitations of Biuret test to detect the existence of peptide bonds in a protein.
An allosteric enzyme is purified and determination of its mass by gel-filtration chromatography yields 240 kDa. Chromatography in the presence of 6M urea yields a 30 kDa species and 90 kDa species. SDS-PAGE in the presence of Beta mercaptoethanol reveals 2 protein bands of 30 kDa and 45kDa. Describe the quatranary structure.
a. An oligopeptide ALVGALGATPTPQMWSHSWRGVSIKS was digested with trypsin.Which method would be most appropriate for separating the products: ion exchange or gel filtration chromatography? Explain.b. Suppose that the peptide was digested with cyanogen bromide. What would be the optimal separation technique? Explain
1. Amino acid analysis of the peptide gave the following residues: Asp Leu Lys Met Phe Tyr. The following facts were observed: Trypsin treatment had no effect. The phenylthiohydantoin released by Edman degradation was C-C-CH2. Brief chymotrypsin treatment yielded several products including a dipeptide and a tetrapeptide. The tetrapeptide contained Leu, Lys and Met is some order. Cyanogen bromide treatment afforded a dipeptide, a tetrapeptide and a free Lys. What is the amino acid sequence for this heptapeptide?
calculate the volume of stock solutions required to make up the buffer solutions that will be used for protein purification. The solutions you need to prepare for purification are: i. Binding Solution A: make up 50 mL 50 mM HEPES buffer (pH 7.5), 300 mM NaCl, 5mM imidazole, 5% (v/v) glycerol ii. Wash Solution B: make up 50 mL 50 mM HEPES buffer (pH 7.5), 300 mM NaCl, 75mM imidazole, 5% (v/v) glycerol iii. Elution Solution C: make up 10 mL 50 mM HEPES buffer (pH 7.5), 300 mM NaCl, 500 mM imidazole, 5% (v/v) glycerol please show your working . Thnk you
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?
You were asked to separate twoproteins from one another by means of iso-electric focussing. The pI value of proteinA is 4.3 and the pI value of protein B is 6.7. Describe how you would carry out thisanalysis. Use also a schematic outline to illustrate your answe
A peptide was analyzed with the following results. What is the primary structure of the peptide? State what each experimental result reveals about the structure and indicate your logic. a) Amino acid analysis: R, C (2 equivalents), G, I, H, M, Y, Vb) After one round of Edman degradation, a mixture of glycine and isoleucine were detected. c) Treatment with beta-mercaptoethanol yielded two peptides, a 4-mer and a 5-mer.