Essential Organic Chemistry, Global Edition
3rd Edition
ISBN: 9781292089034
Author: Paula Yurkanis Bruice
Publisher: PEARSON
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Chapter 17, Problem 57P
A normal polypeptide and a mutant of the polypeptide were hydrolyzed by an endopeptidase under the same conditions. The normal and mutant polypeptide differ by one amino acid. The fingerprints of the peptides obtained from the two polypeptides are shown here. What kind of amino acid substitution occurred as a result of the mutation? (That is, is the substituted amino acid more or less polar than the original amino acid? Is its pI lower or higher?) (Hint: Photocopy the fingerprints, cut them out, and overlay them.)
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A normal polypeptide and a mutant of the polypeptide were hydrolyzed by an endopeptidase under the same conditions. The normal and mutant poly peptide differ by one amino acid. The fingerprints of the peptides obtained from the two polypeptides are shown below. What kind of amino acid substitution occurred as a result of the mutation? (That is, is the substituted amino acid more or less polar than the original amino acid? Is its pI lower or higher?)
As we’ve discussed, a peptide bond is made when amino group of one amino acid combines with the carboxylic acid group of another amino acid (releasing a water molecule in the process). The C-N bond formed in this process is called a peptide bond. Peptide bonds have a few properties that might be unexpected.
b) Another observation is that although the N-H of the peptide bond is able to serve as a H-bond donor the N atom of the peptide bond does not serve as an effective H-bond acceptor. Provide an explanation for this observation, using Lewis structures, VSEPR theory and/or valence bond theory as appropriate.c) It is also fairly accepted that while proteins undergo dynamic motions and conformational changes, and while R groups can freely rotate about Cα, it is generally not possible to freely rotate around a peptide bond. Please explain this observation, using a picture showing relevant orbitals on relevant atoms (your answer for part (a) might provide a useful basis for your reasoning…
Lysine and tryptophan are two amino acids that contain an additional N atom in the R group bonded to the a carbon. While lysine is classified as a basic amino acid because it contains an additional basic N atom, tryptophan is classified as a neutral amino acid. Explain why this difference in classification occurs.
Chapter 17 Solutions
Essential Organic Chemistry, Global Edition
Ch. 17.1 - a. Explain why, when the imidazole ring of...Ch. 17.2 - Prob. 2PCh. 17.3 - Prob. 3PCh. 17.3 - Prob. 4PCh. 17.3 - Prob. 6PCh. 17.4 - Calculate the pI of each of the following amino...Ch. 17.4 - a. Which amino acid has the lowest pI value? b....Ch. 17.5 - What aldehyde is formed when valine is treated...Ch. 17.5 - Prob. 10PCh. 17.5 - Prob. 11P
Ch. 17.5 - Prob. 12PCh. 17.6 - Prob. 13PCh. 17.6 - What amino acid would be formed using the...Ch. 17.6 - What amino acid would be formed when the aldehyde...Ch. 17.7 - Pig liver esterase is an enzyme that catalyzes the...Ch. 17.8 - Prob. 17PCh. 17.8 - Prob. 18PCh. 17.8 - Prob. 19PCh. 17.8 - Prob. 20PCh. 17.10 - Prob. 21PCh. 17.10 - Prob. 22PCh. 17.10 - Why does cyanogen bromide not cleave on the C-side...Ch. 17.10 - Prob. 24PCh. 17.10 - Prob. 26PCh. 17.12 - Prob. 27PCh. 17.13 - a. Which would have the greatest percentage of...Ch. 17 - Draw the predominant form of the following amino...Ch. 17 - What is the pI of serine?Ch. 17 - Prob. 31PCh. 17 - Prob. 32PCh. 17 - Which would have a higher percentage of negative...Ch. 17 - Draw the form of aspartate that predominates at...Ch. 17 - Prob. 35PCh. 17 - A professor was preparing a manuscript for...Ch. 17 - a. Why is the pKa of the glutamate side chain...Ch. 17 - Prob. 38PCh. 17 - Determine the amino acid sequence of a polypeptide...Ch. 17 - Prob. 40PCh. 17 - Prob. 41PCh. 17 - Three peptides were obtained from a trypsin...Ch. 17 - Prob. 43PCh. 17 - After the polypeptide shown here was treated with...Ch. 17 - The disulfide bridges of a polypeptide were...Ch. 17 - -Amino acids can be prepared by treating an...Ch. 17 - Reaction of a polypeptide with carboxypeptidase A...Ch. 17 - Prob. 48PCh. 17 - Prob. 49PCh. 17 - Show how valine can be prepared by a. a Strecker...Ch. 17 - Prob. 51PCh. 17 - Why is proline never found in an -helix?Ch. 17 - Determine the amino acid sequence of a polypeptide...Ch. 17 - Prob. 55PCh. 17 - A chemist wanted to test his hypothesis that the...Ch. 17 - A normal polypeptide and a mutant of the...
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- On complete hydrolysis, a polypeptide gives two alanine, one leucine, one methionine, one phenylalanine, and one valine residue. Partial hydrolysis gives the following fragments: Ala-Phe, Leu-Met, Val-Ala, Phe-Leu. It is known that the first amino acid in the sequence is valine and the last one is methionine. What is the complete sequence of amino acids?arrow_forward22-42 (a) How many atoms of the peptide bond lie in the same plane? (b) Which atoms are they?arrow_forwardFor the tripeptide SerValMet a. What amino acid is located at the peptides N-terminal end? b. What amino acid is located at the peptides C-terminal end? c. How many peptide bonds are present? d. How many amide linkages are present?arrow_forward
- What are the structures of the amino acids that result from the hydrolysis of all the peptide bonds in the peptide? HO 'N' HO, NH2 H COOH draw structure ... draw structure ... draw structure .. left structure middle structure right structurearrow_forward4: Draw structures from notations or notations from structures, for the following dipeptides. Look up in book for the structures of various amino acids and their names (and notations). (EOCQ 60) Hints for drawing a dipeptide from the specified amino acids. From the given symbols (Ser, Thr, etc), draw the structures for the amino acids in the specified order example, for Ser-Thr, draw Serine first and then Threonine). Then remove the OH from the first amin and one H (from the N atom) on the second amino acid. Then join the remaining fragments; that give the dipeptide formed. In these reactions, H2O is formed as a side product; but it is implied, and you have to show it in your answers. The following equation illustrates that. Here, R and R' are symbolic. In an actual question, you must the actual structures for the amino acids (Table 16.3 in the book). O H || | Н.N— CH— С-N-CH—С-ОН H,N-CH-C–OH + H,N-CH-Ċ–OH R' R. R' (H2O is a sid no need t Amino acid 2 dipeptide Amino acid 1 а. Cys-Ser…arrow_forwardResearchers analysed a glycopeptide (a peptide carrying one or several oligosaccharide groups) and determined both the sequence of the peptide and the sequence of the sugar molecule. The latter was identified as a diholoside coupled to the peptide by an osidic bond. The systematic name of this sugar is: B-D-glucopyranosyl-(1→4)-ß-D-galactopyranose. : Represent the chemical formula of this diholoside in a way that all oses are Question 1 represented according to the Haworth convention. Apart from the furane and/or pyrane cycles all atoms of this molecule must be given.arrow_forward
- A peptide has the sequence Glu–His–Trp–Ser–Gly–Leu–Arg–Pro–Gly The p?a values for the peptide’s side chains, terminal amino groups, and carboxyl groups are provided in the table. Amino acid Amino pKa Carboxyl pKa Side‑chain pKa glutamate 9.609.60 2.342.34 4.254.25 histidine 9.179.17 1.821.82 6.006.00 tryptophan 9.399.39 2.382.38 serine 9.159.15 2.212.21 glycine 9.609.60 2.342.34 leucine 9.609.60 2.362.36 arginine 9.049.04 2.172.17 12.4812.48 proline 10.9610.96 1.991.99 Calculate the net charge of the molecule at pH 11 and estimate the isoelectric point (pI)(pI) for this peptide.arrow_forwardNet charge and isoelectric point of an amino acid with an ionizable side group.Consider the net charge and isoelectric point of an amino acid with ionizable side (R-) group.(a) Identify the acidic amino acid(s) capable of having a negatively charged carboxyl side group.(b) Identify the basic amino acid(s) capable of having a positively charged amino side group.(c) For an amino acid with a side (R-) chain that can ionize to a negative charge, derive a general expression in terms of measured pH and known pKa values of α-carboxyla-amino (pKca), α-amino(pKaa),and side group (pKRa), respectively, for the net charge of an amino acid Consider the net charge and isoelectric point of an amino acid with ionizable side (R-) group.(d) For an amino acid with a side (R-) chain that can ionize to a positive charge, derive a general expression in terms of measured pH and known pKa values ofα-carboxyl (pKca), α-amino (pKaa), and side group (pKRa), respectively, for the net charge of the amino acid.(e)…arrow_forwardHow many different tetrapeptides can be made under the following conditions? Q.) All 20 amino acids can be used, but each only once.arrow_forward
- Secondary structure is: the sequence of the amino acids on the peptide-bonded chain. dependent on the interaction of multiple polypeptide chains to make up the functional protein. the arrangements of amino acid side groups within a protein. based on the arrangement in space of the atoms in the peptide backbone. the three-dimensional arrangement of all the atoms in the protein.arrow_forwardWhich of these amino acids has a hydrophobic side chain?arrow_forwardGive the amino acid sequence of each peptide using the fragments obtained by partial hydrolysis of the peptide with acid. a. a tetrapeptide that contains Ala, Gly, His, and Tyr, which is hydrolyzed to the dipeptides His-Tyr, Gly-Ala, and Ala-His b. a pentapeptide that contains Glu, Gly, His, Lys, and Phe, which is hydrolyzed to His-Gly-Glu, Gly-Glu-Phe, and Lys-Hisarrow_forward
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