Organic Chemistry
9th Edition
ISBN: 9781305080485
Author: John E. McMurry
Publisher: Cengage Learning
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Question
Chapter 26.1, Problem 2P
Interpretation Introduction
Interpretation:
The reason why cysteine has R configuration while all the others have S configuration.
Concept introduction:
Except glycine, all the other 19 amino acids have chiral centers and hence can occur as two enantiomers. But the naturally occurring enantiomers resemble the L sugars, i.e. placing the CO2- group at the top and pointing the side chain downwards and the NH3 group on the left. These usually have S configuration, which is dependent on the priority of the attached molecules. But this is not the case for cysteine as it has R configuration.
To determine:
Why cysteine is the L amino amino acid that occurs in R configuration naturally?
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Vasopressin is a peptide hormone synthesized by the hypothalamus; in its reduced form it has the structure shown.
NH2
HS
H
H
H
H H
*H3N°
NH2
N'
SH
NH2
ОН
Vasopressin
NH
*H2N=
NH2
This structure is incorrect in that one of the amino acids is shown in the D-configuration, rather than the L-. Which one is it?
What is the amino acid sequence of this peptide?
Enter
your answer using the single letter abbretiavions for the amino acids; i.e. GPT, not Gly-Pro-Thr.
What is the net charge of this peptide at physiological pH?
ZI
IZ
ZI
IZ
ZI
Draw the stereoisomers of the following amino acids. Indicate pairs of enantiomers and pairs of diastereomers.
What type of interaction (IMF) would be present between side chains of the following amino acid residues? Explain your answers.
a) 2 phenylalanine residues
b) Methionine and valine residues
c) Glutamate and arginine residues
Chapter 26 Solutions
Organic Chemistry
Ch. 26.1 - How many of the -amino acids shown in Table 26-1...Ch. 26.1 - Prob. 2PCh. 26.1 - Prob. 3PCh. 26.2 - Hemoglobin has pI=6.8. Does hemoglobin have a net...Ch. 26.3 - Show how you could prepare the following -amino...Ch. 26.3 - What alkyl halides would you use to prepare the...Ch. 26.3 - Prob. 7PCh. 26.4 - There are six isomeric tripeptides that contain...Ch. 26.4 - Draw the structure of M-P-V-G, and indicate its...Ch. 26.5 - Prob. 10P
Ch. 26.5 - Prob. 11PCh. 26.6 - The octapeptide angiotensin II has the sequence...Ch. 26.6 - Prob. 13PCh. 26.6 - Prob. 14PCh. 26.6 - Give the amino acid sequence of hexapeptides that...Ch. 26.7 - Prob. 16PCh. 26.7 - Write all five steps required for the synthesis of...Ch. 26.10 - Prob. 18PCh. 26.SE - Identify the following amino acids:Ch. 26.SE - Prob. 20VCCh. 26.SE - Isoleucine and threonine are the only two amino...Ch. 26.SE - Prob. 22VCCh. 26.SE - Give the sequence of the following tetrapeptide:Ch. 26.SE - Prob. 24MPCh. 26.SE - The chloromethylated polystyrene resin used for...Ch. 26.SE - Prob. 26MPCh. 26.SE - Prob. 27MPCh. 26.SE - Prob. 28MPCh. 26.SE - Except for cysteine, only S amino acids occur in...Ch. 26.SE - Prob. 30APCh. 26.SE - Prob. 31APCh. 26.SE - Show the structures of the following amino acids...Ch. 26.SE - Prob. 33APCh. 26.SE - Using both three- and one-letter codes for amino...Ch. 26.SE - Prob. 35APCh. 26.SE - Show how you could use the acetamidomalonate...Ch. 26.SE - Prob. 37APCh. 26.SE - Show how you could prepare the following amino...Ch. 26.SE - Prob. 39APCh. 26.SE - Predict the product of the reaction of valine with...Ch. 26.SE - Prob. 41APCh. 26.SE - Prob. 42APCh. 26.SE - Propose two structures for a tripeptide that gives...Ch. 26.SE - Show the steps involved in a synthesis of...Ch. 26.SE - Prob. 45APCh. 26.SE - Prob. 46APCh. 26.SE - Prob. 47APCh. 26.SE - Which of the following amino acids are more likely...Ch. 26.SE - Leuprolide is a synthetic nonapeptide used to...Ch. 26.SE - The -helical parts of myoglobin and other proteins...Ch. 26.SE - Prob. 51APCh. 26.SE - Cytochrome c is an enzyme found in the cells of...Ch. 26.SE - Prob. 53APCh. 26.SE - Prob. 54APCh. 26.SE - Prob. 55APCh. 26.SE - What is the structure of a nonapeptide that gives...Ch. 26.SE - Oxytocin, a nonapeptide hormone secreted by the...Ch. 26.SE - Aspartame, a nonnutritive sweetener marketed under...Ch. 26.SE - Prob. 59APCh. 26.SE - Prob. 60APCh. 26.SE - Prob. 61APCh. 26.SE - Prob. 62AP
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