Textbook Question
Draw the pH–activity profile for an enzyme that has one catalytic group at the active site:
a. the catalytic group is a general-acid catalyst with a pKa = 5.6.
925
views
Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
All textbooks
Bruice 8th EditionCh. 22 - Catalysis in Organic Reactions and in Enzymatic ReactionsProblem 16
Bruice 8th EditionCh. 22 - Catalysis in Organic Reactions and in Enzymatic ReactionsProblem 16Chapter 23, Problem 16
Which of the following C-terminal peptide bonds is more readily cleaved by carboxypeptidase A? Explain your choice.
Ser-Ala-Leu or Ser-Ala-Asp
Verified step by step guidance1
Understand the role of carboxypeptidase A: Carboxypeptidase A is an enzyme that cleaves the C-terminal peptide bond of a polypeptide chain. It preferentially cleaves bonds where the C-terminal amino acid has a nonpolar or hydrophobic side chain, such as aliphatic or aromatic residues.
Analyze the C-terminal amino acid in Ser-Ala-Leu: The C-terminal amino acid here is Leu (Leucine), which has a nonpolar, hydrophobic side chain. This makes it a good substrate for carboxypeptidase A.
Analyze the C-terminal amino acid in Ser-Ala-Asp: The C-terminal amino acid here is Asp (Aspartic acid), which has a polar, negatively charged side chain. Carboxypeptidase A is less efficient at cleaving bonds involving polar or charged residues.
Compare the two peptide sequences: Since Leu is nonpolar and hydrophobic, it is more readily cleaved by carboxypeptidase A compared to Asp, which is polar and charged.
Conclude the reasoning: The peptide Ser-Ala-Leu is more readily cleaved by carboxypeptidase A than Ser-Ala-Asp due to the preference of the enzyme for nonpolar, hydrophobic C-terminal residues like Leu over polar, charged residues like Asp.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
5mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Carboxypeptidase A Function
Carboxypeptidase A is an enzyme that catalyzes the hydrolysis of peptide bonds at the C-terminal end of proteins and peptides. It specifically cleaves bonds adjacent to aromatic or branched-chain amino acids, which influences its substrate specificity. Understanding the enzyme's mechanism and preferred substrates is crucial for predicting which peptide bond will be cleaved more readily.
Recommended video:
Guided course
02:36
Identifying Functional Groups
Peptide Bond Characteristics
Peptide bonds are formed between the carboxyl group of one amino acid and the amino group of another, resulting in a covalent bond. The nature of the amino acids involved, particularly their side chains, can affect the stability and reactivity of the peptide bond. In this context, the presence of an acidic side chain, like aspartic acid (Asp), can influence the cleavage by carboxypeptidase A.
Recommended video:
1:24Peptides Example 1
Amino Acid Properties
Amino acids have distinct properties based on their side chains, which can affect enzyme interactions. For instance, Serine (Ser) and Alanine (Ala) are neutral, while Aspartic acid (Asp) is negatively charged. The presence of Asp at the C-terminus in the peptide Ser-Ala-Asp may make this bond more favorable for cleavage by carboxypeptidase A compared to the neutral peptide Ser-Ala-Leu.
Recommended video:
Guided course
04:10The 7 Ionizable Amino Acids
Related Practice
Textbook Question
Draw the pH–activity profile for an enzyme that has one catalytic group at the active site:
b. the catalytic group is a general-base catalyst with a pKa = 7.2.
1008
views
Textbook Question
Why do the nitro groups change the relative leaving tendencies of the carboxy and 2,4-dinitrophenoxy groups in the tetrahedral intermediate in Problem 11?
924
views
Textbook Question
The pH–activity profile for glucose-6-phosphate isomerase indicates the participation of a group with a pKa = 6.7 as a basic catalyst and a group with a pKa = 9.3 as an acid catalyst. Draw the pH–activity profile and identify the amino acids that participate in the catalysis.
1030
views
Textbook Question
Show all the products, including their configurations, that are obtained from the above reaction.
1023
views
Textbook Question
Which of the following amino acid side chains can help remove a proton from the α-carbon of an aldehyde?
3080
views