Organic Chemistry (8th Edition)
8th Edition
ISBN: 9780134042282
Author: Paula Yurkanis Bruice
Publisher: PEARSON
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Textbook Question
Chapter 21, Problem 51P
A titration curve is a plot of the pH of a solution as a function of added equivalents of hydroxide ion. As hydroxide ion is added to the aqueous solution, the pH increases because hydroxide ion removes protons from the solution. The pH flattens out when hydroxide ion can remove a proton from an ionziable group of an amino acid rather than a proton from the solution. Identify the amino acids that give the titration curves below.
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Chapter 21 Solutions
Organic Chemistry (8th Edition)
Ch. 21.1 - a. Explain why, when the imidazole ring of...Ch. 21.2 - a. Which isomer(R)-alanine or (S)-alanineis...Ch. 21.2 - Prob. 4PCh. 21.3 - Prob. 5PCh. 21.3 - Prob. 6PCh. 21.3 - Draw the predominant form for glutamate in a...Ch. 21.3 - a. Why is the pKa of the glutamate side chain...Ch. 21.4 - Calculate the pI of each of the following amino...Ch. 21.4 - a. Which amino acid has the lowest pI value? b....Ch. 21.4 - Prob. 12P
Ch. 21.4 - Prob. 13PCh. 21.4 - Explain why the pI of lysine is the average of the...Ch. 21.5 - What aldehyde is formed when valine is treated...Ch. 21.5 - Prob. 16PCh. 21.5 - Prob. 17PCh. 21.5 - Prob. 18PCh. 21.5 - Prob. 19PCh. 21.6 - Why is excess ammonia used in the preceding...Ch. 21.6 - Prob. 21PCh. 21.6 - What amino acid is formed using the...Ch. 21.6 - Prob. 23PCh. 21.6 - What amino acid is formed when the aldehyde used...Ch. 21.7 - Esterase is an enzyme that catalyzes the...Ch. 21.8 - Draw the tetrapeptide Ala-Thr-Asp-Asn and indicate...Ch. 21.8 - Draw the resonance contributors of the peptide...Ch. 21.8 - Which bonds in the backbone of a peptide can...Ch. 21.9 - An opioid pentapeptide has the following...Ch. 21.9 - What is the configuration about each of the...Ch. 21.9 - Glutathione is a tripeptide whose function is to...Ch. 21.10 - What dipeptides would be formed by heating a...Ch. 21.10 - Suppose you are trying to synthesize the dipeptide...Ch. 21.10 - Show the steps in the synthesis of the...Ch. 21.10 - a. Calculate the overall yield of bradykinin when...Ch. 21.11 - Show the steps in the synthesis of the...Ch. 21.13 - Prob. 37PCh. 21.13 - In determining the primary structure of insulin,...Ch. 21.13 - A decapeptide undergoes partial hydrolysis to give...Ch. 21.13 - Explain why cyanogen bromide does not cleave on...Ch. 21.13 - Indicate the peptides produced from cleavage by...Ch. 21.14 - Prob. 43PCh. 21.14 - Three peptides were obtained from a trypsin...Ch. 21.14 - Prob. 45PCh. 21.15 - How would a protein that resides in the nonpolar...Ch. 21.16 - a. Which would have the greatest percentage of...Ch. 21.17 - When apples that have been cut are exposed to...Ch. 21 - Glycine has pK2 values of 2.34 and 9.60. At what...Ch. 21 - Prob. 50PCh. 21 - A titration curve is a plot of the pH of a...Ch. 21 - Prob. 52PCh. 21 - Aspartame (its structure is on page 1007) has a pl...Ch. 21 - Draw the form of aspartate that predominates at...Ch. 21 - Show how phenylalanine can be prepared by...Ch. 21 - A professor was preparing a manuscript for...Ch. 21 - What aldehydes are formed when the following amino...Ch. 21 - Prob. 58PCh. 21 - Determine the amino acid sequence of a polypeptide...Ch. 21 - Prob. 60PCh. 21 - Prob. 61PCh. 21 - Which is the more effective buffer at...Ch. 21 - Identify the location and type of charge on the...Ch. 21 - Draw the product obtained when a lysine side chain...Ch. 21 - After the polypeptide shown below was treated with...Ch. 21 - Treatment of a polypeptide with 2-mercaptoethanol...Ch. 21 - Show how aspartame can be synthesized using DCCD.Ch. 21 - -Amino acids can be prepared by treating an...Ch. 21 - Reaction of a polypeptide with carboxypeptidase A...Ch. 21 - a. How many different octapeptides can be made...Ch. 21 - Glycine has pKa values of 2.3 and 9.6. Do you...Ch. 21 - A mixture of 15 amino acids gave the fingerprint...Ch. 21 - Write the mechanism for the reaction of an amino...Ch. 21 - Prob. 74PCh. 21 - Show how valine can be prepared by a. a...Ch. 21 - The primary structure of -endorphin, a peptide...Ch. 21 - A chemist wanted to test his hypothesis that the...Ch. 21 - Propose a mechanism for the rearrangement of the...Ch. 21 - A normal polypeptide and a mutant of the...Ch. 21 - Determine the amino acid sequence of a polypeptide...
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- Write the chemical equilibrium and expression for the equilibrium constants for the ionization of (a) tartaric acid. (b) malic acid.arrow_forwardFor the amino acid Lysine draw the two predominant species when the pH is 10,You do not need to draw the entire R group.arrow_forwardWhen a weak monoprotic acid (HA) is titrated with NaOH, which of the following forms of the acid is present at buffering region? In the titration of a weak acid with an unknown solution with NaOH, which of the following goes into the burette? An amino acid can be considered as a polyprotic acid, true or false?arrow_forward
- Describe three effects of pH on ionization of a weak acid or base that impact biological stability of a protein.arrow_forwardAmino acids have different protonation states at different pH. The protonation states of the amine and carboxylic acid functional groups can vary at different pH. In addition, the side chain can have different ionic states. Choose the protonation state of lysine at physiological pH. H₂N- H NH₂ I OH H₂N. H₂N H 0=6 NH₂ IV NH₂ || OH H₂N. H H₂N H NH₂ O V NH₂ |||arrow_forwardDraw a structural formula for the major ionic form of the amino acid shown below when in aqueous solution at pH 1.5. HO -CH₂CHCOH *NH3 tyrosinearrow_forward
- Alanine is a diprotic amino acid with a pKa = 2.344 for the carboxylic group and a pKa = 9.868 for the ammonium group. Estimate the pH of a solution of 0.340 M alanine. Answer using two significant figures.arrow_forwardAll amino acids have two ionizable functional groups: an α‑amino group (average p?a of 9.4) and an α‑carboxylic acid group (average p?a of 2.2). Aspartic acid has an ionizable side chain (R group) with a p?a of about 3.8. One of the possible ionization states of aspartic acid is shown in the image. The protonated form of the R group of aspartic acid is shown in the structure. The ratio of the protonated form to the charged (deprotonated) form depends on the p?a of the R group and the pH of the solution. Select all the pH values at which the charged form of the R group would predominate.arrow_forwardExplain which amino acids are acidic, which are basic, and which are neutral. Use theisoelectric point to predict whether a given amino acid will be positively charged,negatively charged, or neutral at a given pH.arrow_forward
- Calculate the pH of a 0.100 M alanine (HL/intermediate form) solution. pKb1 = 4.29 and pKb2 = 11.67.arrow_forwardDraw the sequential transition of glutamic acid as it passes from its fully protonated form to its fully deprotonated form as the pH rises. If the pH of an amino acid solution is lowered by adding an acid, like , the group of glutamic acid accepts the proton, acid, to form a positive ion.arrow_forwardWhich amino acid has the greatest amount of negative charge at pH = 6.20?arrow_forward
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