Organic Chemistry
7th Edition
ISBN: 9780321803221
Author: Paula Y. Bruice
Publisher: Prentice Hall
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Chapter 25.10, Problem 17P
Acid-catalyzed dehydration reactions are normally E1 reactions. Why is the acid-catalyzed dehydration in the second reaction of the citric acid cycle an E2 reaction?
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Acid-catalyzed dehydration reactions are normally E1 reactions. Why is the acid-catalyzed dehydration in the second reaction of the citric acid cycle an E2 reaction?
Step 7 of the citric acid cycle is shown. Which statement best describes what occurs
in this step?
CO₂
1
CH
||
CH
+ H₂O
CO₂
fumarate
CO₂™
fumarase HO C-H
CH₂
CO₂
malate
A)
Fumarate undergoes hydrogenation with hydrogens and electrons provided
by the enzyme fumarase.
B) Fumarate undergoes hydration with the aid of the enzyme fumarase.
C) Fumarate undergoes hydrolysis with the aid of the enzyme fumarase.
D) Fumarate undergoes reduction with the aid of the cofactor fumarase.
4. Liver alcohol dehydrogenase (LADH) catalyzes a reversible, pH-dependent oxidation of an alcohol
to an aldehyde according to the following reaction:
LADH
RCH2OH
+
NAD*
RCHO
+
NADH
+
H*
where NAD* and NADH are, respectively, the oxidized and reduced forms of the cofactor nicotin-amide
adenine dinucleotide. While the reaction is actually a two-substrate reaction, it proceeds like a one-
substrate reaction through a so-called compulsory-ordered ternary complex mechanism. It has been
shown through kinetic studies that, in the case of primary alcohols, the enzyme binds first the cofactor
forming a binary enzyme-NAD* complex that then binds the second substrate, the alcohol, to form a
ternary enzyme-NAD*-substrate complex in which the oxidation of the alcohol proceeds with reduction
of the cofactor.
While the enzyme catalyzes oxidation of various steroids as well as ingested ethanol, it also catalyzes
the oxidation of methanol CH3OH, forming the extremely toxic product formaldehyde HCHO.…
Chapter 25 Solutions
Organic Chemistry
Ch. 25.6 - Prob. 2PCh. 25.6 - Prob. 3PCh. 25.6 - Why does the OH group add to the -carbon rather...Ch. 25.6 - Prob. 5PCh. 25.6 - How many molecules of NADH are formed from the...Ch. 25.7 - Prob. 7PCh. 25.7 - Prob. 8PCh. 25.7 - The oxidation of glyceraldehyde-3-phosphate to...Ch. 25.7 - Prob. 10PCh. 25.8 - Prob. 11P
Ch. 25.8 - Prob. 12PCh. 25.8 - Prob. 13PCh. 25.8 - Propose a mechanism for the reduction of...Ch. 25.9 - Prob. 15PCh. 25.9 - Prob. 16PCh. 25.10 - Acid-catalyzed dehydration reactions are normally...Ch. 25.10 - Prob. 18PCh. 25.10 - Prob. 19PCh. 25.10 - Acid-catalyzed dehydration reactions are normally...Ch. 25.10 - Prob. 21PCh. 25.10 - Prob. 22PCh. 25.11 - Prob. 23PCh. 25.12 - a. What is the name of the enzyme that converts...Ch. 25.15 - Prob. 25PCh. 25.16 - Prob. 26PCh. 25.16 - Prob. 27PCh. 25.17 - Propose mechanisms for the Claisen condensation...Ch. 25.17 - Prob. 29PCh. 25.17 - Propose a mechanism for the conversion of...Ch. 25.17 - Propose a mechanism for the biosynthesis of...Ch. 25.17 - Propose a mechanism for the conversion of the E...Ch. 25.17 - The fluoro-substitued geranyl pyrophosphate shown...Ch. 25.17 - Prob. 35PCh. 25.18 - Draw the individual 1,2-hydride and 1,2-methyl...Ch. 25 - Prob. 38PCh. 25 - Prob. 39PCh. 25 - Prob. 40PCh. 25 - Prob. 41PCh. 25 - Prob. 42PCh. 25 - Prob. 43PCh. 25 - Prob. 44PCh. 25 - Prob. 45PCh. 25 - Prob. 46PCh. 25 - Prob. 47PCh. 25 - Prob. 48PCh. 25 - Prob. 49PCh. 25 - Prob. 50PCh. 25 - Prob. 51PCh. 25 - Prob. 52PCh. 25 - Prob. 53PCh. 25 - Prob. 54PCh. 25 - Prob. 55PCh. 25 - Prob. 56PCh. 25 - Prob. 57PCh. 25 - Prob. 58PCh. 25 - Prob. 59PCh. 25 - Prob. 60PCh. 25 - Prob. 61PCh. 25 - Prob. 62PCh. 25 - UDP-galactose-4-epimerase converts UDP-galactose...Ch. 25 - A student is trying to determine the mechanism for...Ch. 25 - What would be the results of the experiment in...Ch. 25 - Prob. 66PCh. 25 - Propose a mechanism for the biosynthesis of...Ch. 25 - Eudesmol is a sesquiterpene found in eucalyptus....
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- One of the steps in the pentose phosphate pathway for glucose catabolism is the reaction of sedoheptulose 7-phosphate with glyceraldehydes 3-phosphate in the presence of a transaldolase to yield erythrose 4-phosphate and fructose 6-phosphate. (a) The first part of the reaction is the formation of a protonated Schiff base of sedoheptulose 7-phosphate with a lysine residue in the enzyme followed by a retro-aldol cleavage to give an enamine plus erythrose 4-phosphate. Show the structure of the enamine and the mechanism by which it is formed. (b) The second part of the reaction is a nucleophilic addition of the enamine to glyceraldehyde 3-phosphate followed by hydrolysis of the Schiff base to give fructose 6-phosphate. Show the mechanism.arrow_forwardLinoleic acid is shown below. What makes this fatty acid particularly susceptible to autoxidation? 1. The red CH bond has a low bond dissociation energy because it is doubly allylic. 2. The red CH bond has a high bond dissociation energy because it is doubly allylic. 3. The red CH bond is the most accessible to reaction with O2 because it is the least sterically crowded CH bond. 4. Both 2 and 3.arrow_forwardThere are eight chemical reactions that occur in the citric acid cycle process. The reactions of the citric acid cycle are shown in the figure below. You were introduced to several classes of organic reactions. These classes include esterification, decarboxylation, hydration reactions, dehydration of alcohols, oxidation of alcohols, oxidation of aldehydes, reduction of aldehydes, and reduction of ketones. Find at least one of these reaction classes in the citric acid cycle. List the reaction number and the reaction. Write a sentence or two on how you were able to make the classification.arrow_forward
- Draw the products that form when the thioester CH3CH2CH2COSCoA is hydrolyzed with water. Differentiate products by greater or lesser molecular weight.arrow_forwardCholesterol-lowering drugs commonly target O HMG-COA synthase, the enzyme that catalyzes the synthesis of mevalonate O pyruvate decarboxylase complex, which catalyzes the synthesis of acetyl-CoA O mevalonate, an isoprene O HMG-COAreductase, the rate-limiting enzyme in cholesterol biosynthesis O HMG-CoA synthase, the enzyme that catalyzes the first step in cholesterol biosynthesisarrow_forwardKinetic versus thermodynamic. The reaction of NADH with oxygen to produce NAD+NAD* and H2OH2O is very exergonic, yet the reaction of NADH and oxygen takes place very slowly. Why does a thermodynamically favorable reaction not occur rapidly?arrow_forward
- Present the 3-membered ring pathway for the following reactions. Cl2 Br CH3OHarrow_forwardH-C-U-o 27. The following is step 3 of the citric acid cycle. What is the functional transformation that occurs in the first part of this step? group COO COO NAD* NADH + H* CH2 CH2 0 H-C-C CH2 H-C-H H-C-COO- Но-с-н COO COO Isocitrate a-ketoglutarate A) A ketone and an alcohol change positions. C) The -COO is transformed. B) An alcohol becomes a ketone. D) The alcohol becomes an aldehyde. 28. The following is step 3 of the citric acid cycle. What is the identity of the Molecule represented by I? COO COO NAD* NADH + H* I COO CH2 CH2 0 H-C-C CH2 H-C-H H-C-COO- HO-C-H COO COO Isocitrate a-ketoglutarate A) Acetate B) GTP C) NADH D) FADH2 E) CO2arrow_forwardDraw Intermediate (CH3)2NH Deprotonation Drawingarrow_forward
- 1. Fill in the boxes to complete the reaction below: LIAIH4, THFarrow_forwardThe number of ATP molecules consumed and produced during glycolysis under anaerobic conditions are summarized in the following diagram (the ATP hydrolysis and synthesis reactions are shown in green). Phosphate Carbon atom 2 ATP 2 ADP ●●●●●● Glucose I Energy-Investing Phase O 2 ATP O 6 ATP O 1 ATP 8 ATP NADH + NAD* +H* O 4 ATP ●●●● 2 ADP 2 ATP NADH + NAD +H Based on the diagram above, for each glucose molecule broken down, what is the net energy yield of glycolysis in terms of ATP under anaerobic conditions? Pyruvate 2 ADP 2 ATP ●●●●● Energy-Generating Phase Pyruvatearrow_forward4. Glycolysis is a metabolic pathway that converts glucose into pyruvate while synthesizing high-energy molecules. During one step of Glycolysis, glucose-6-phosphate (an aldose) is converted to fructose-6-phosphate (a ketose) via an ene-diol intermediate. OH OH O OP OH OH ОН ОН glucose-6-phosphate OH OH OH OP OH fructose-6-phosphate Draw arrow pushing mechanism to describe this isomerization. Use B: and HA as surrogates for basic/acidic amino acid residues.arrow_forward
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