Textbook Question
Aldolase shows no activity if it is incubated with iodoacetic acid before fructose-1,6-bisphosphate is added to the reaction mixture. What causes this loss of activity?
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Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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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
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Bruice 8th EditionCh. 22 - Catalysis in Organic Reactions and in Enzymatic ReactionsProblem 27
Bruice 8th EditionCh. 22 - Catalysis in Organic Reactions and in Enzymatic ReactionsProblem 27Chapter 23, Problem 27
In glycolysis, why must glucose-6-phosphate isomerize to fructose-6-phosphate (Section 22.12 ) before the cleavage reaction with aldolase occurs?
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Understand the context: Glycolysis is a metabolic pathway that breaks down glucose into pyruvate, generating energy. The isomerization of glucose-6-phosphate (G6P) to fructose-6-phosphate (F6P) is a key step in this pathway.
Recognize the structural difference: Glucose-6-phosphate is a six-membered ring (a pyranose), while fructose-6-phosphate is a five-membered ring (a furanose). This structural change is necessary for subsequent reactions.
Identify the cleavage reaction: The aldolase enzyme cleaves fructose-1,6-bisphosphate (a derivative of F6P) into two three-carbon molecules: dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P). This reaction requires a ketose sugar (like fructose) rather than an aldose sugar (like glucose).
Explain the need for isomerization: The isomerization step converts G6P (an aldose) into F6P (a ketose), which is essential for the aldolase enzyme to recognize and cleave the molecule efficiently. Without this isomerization, the cleavage reaction would not proceed correctly.
Conclude the importance: The isomerization ensures that the glycolytic pathway progresses smoothly by preparing the molecule for the aldolase-catalyzed cleavage, which is a critical step in energy production.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Glycolysis
Glycolysis is a metabolic pathway that converts glucose into pyruvate, producing energy in the form of ATP. It consists of ten enzyme-catalyzed reactions and is crucial for cellular respiration. Understanding glycolysis is essential for grasping how glucose is processed in the body and the significance of each intermediate formed during the pathway.
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Intro to Glycolysis Example 1
Isomerization
Isomerization is a chemical process where a molecule is transformed into another molecule with the same atoms but in a different arrangement. In glycolysis, the conversion of glucose-6-phosphate to fructose-6-phosphate is an example of isomerization, which prepares the molecule for subsequent reactions. This step is vital as it alters the structure to facilitate the cleavage by aldolase.
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Aldolase Reaction
The aldolase reaction is a key step in glycolysis where fructose-1,6-bisphosphate is split into two three-carbon molecules: dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. This reaction is dependent on the correct structure of the substrate, which is why the isomerization of glucose-6-phosphate to fructose-6-phosphate is necessary. The aldolase enzyme specifically recognizes the fructose structure for efficient cleavage.
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Related Practice
Textbook Question
Draw the mechanism for the hydroxide ion–catalyzed cleavage of fructose-1,6-bisphosphate.
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Textbook Question
Which of the following two compounds eliminates HBr more rapidly in a basic solution?
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Textbook Question
Which compound forms an anhydride more rapidly?
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Textbook Question
Which of the following amino acid side chains can form an imine with a substrate?
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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.
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