Essential Organic Chemistry (3rd Edition)
3rd Edition
ISBN: 9780321937711
Author: Paula Yurkanis Bruice
Publisher: PEARSON
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Chapter 18.9, Problem 16P
Acetolactate synthase is another TPP-requiring enzyme. It, too, catalyzes the decarboxylation of pyruvate, but it transfers the resulting acyl group to another molecule of pyruvate, forming acetolactate. This is the first step in the biosynthesis of the amino acids valine and leucine. Propose a mechanism for this reaction.
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Triosephosphate isomerase (TIM) catalyzes the conversion of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate. The enzyme’s catalytic groups are Glu 165 and His 95. In the first step of the reaction, these catalytic groups function as a general-base and a general-acid catalyst, respectively. Propose a mechanism for the reaction.
Acetolactate synthase is another TPP-requiring enzyme. It transfers the acyl group of pyruvate to another molecule of pyruvate, forming acetolactate. This is the first step in the biosynthesis of the amino acids valine and leucine. Propose a mechanism for this reaction.
Please draw by hand. Triosephosphate isomerase (TIM) catalyzes the conversion of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate. The enzyme's catalytic groups are Glu 165 and His 95. In the first step of the reaction, these catalytic groups function as a base and an acid catalyst, respectively. Propose a mechanism for the reaction.
ОН
2-03Р0
ОН
dihydroxyacetone phosphate
triosephosphate isomerase
2-03РО.
H
glyceraldehyde-3-phosphate
FYI Glu is glutamic acid and his is histadine
Chapter 18 Solutions
Essential Organic Chemistry (3rd Edition)
Ch. 18.1 - Prob. 1PCh. 18.2 - If H218O were used to hydrolyze lysozyme, which...Ch. 18.3 - Which of the following amino acid side chains can...Ch. 18.3 - Arginine and lysine side chains fit into trypsins...Ch. 18.4 - Which of the following amino acid side chains can...Ch. 18.4 - Prob. 6PCh. 18.5 - Prob. 7PCh. 18.5 - Draw the mechanism for the hydroxide-ion-catalyzed...Ch. 18.5 - What advantage does the enzyme gain by forming an...Ch. 18.7 - Prob. 10P
Ch. 18.7 - Prob. 11PCh. 18.8 - How many conjugated double bonds are there in a....Ch. 18.8 - Instead of adding to the 4a-position and...Ch. 18.8 - In succinate dehydrogenase, FAD is covalently...Ch. 18.8 - Prob. 15PCh. 18.9 - Acetolactate synthase is another TPP-requiring...Ch. 18.9 - Acetolactate synthase can also transfer the acyl...Ch. 18.9 - Prob. 18PCh. 18.9 - Prob. 19PCh. 18.10 - Prob. 21PCh. 18.11 - Prob. 23PCh. 18.11 - Which compound is more easily decarboxylated?Ch. 18.11 - Explain why the ability of PLP to catalyze an...Ch. 18.11 - Explain why the ability of PLP to catalyze an...Ch. 18.12 - What groups are interchanged in the following...Ch. 18.13 - Why is the coenzyme called tetrahydrofolate?Ch. 18.13 - What amino acid is formed by the following...Ch. 18.13 - How do the structures of tetrahydrofolate and...Ch. 18.13 - What is the source of the methyl group in...Ch. 18 - Prob. 32PCh. 18 - Prob. 33PCh. 18 - From what vitamins are the following coenzymes...Ch. 18 - Prob. 35PCh. 18 - For each of the following reaction, name both the...Ch. 18 - Explain why serine proteases do not catalyze...Ch. 18 - Prob. 38PCh. 18 - For each of the following enzyme catalyzed...Ch. 18 - Trisephosphate isomerase (TIM) catalyzes the...Ch. 18 - Prob. 41PCh. 18 - What acyl groups have we seen transferred by...Ch. 18 - When UMP is dissolved in T2O, exchange of T for H...Ch. 18 - Prob. 44PCh. 18 - When transaminated, the three branched-chain amino...Ch. 18 - Aldolase shows no activity if it is incubated with...
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- In the pentose phosphate pathway for degrading sugars, ribulose 5-phosphate is converted to ribose 5-phosphate. Propose a mechanism for the isomerization.arrow_forwardOne 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_forwardSuggest a name for an enzyme that catalyzes each of the following reactions. a. Hydrolysis of lactose b. Oxidation of nitrite c. Decarboxylation of citrate d. Reduction of oxalatearrow_forward
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- The same E1–E2–E3 multienzyme structure found in the pyruvate dehydrogenase and the a-ketoglutarate dehydrogenase complexes is also used in the branched-chain a-ketoacid dehydrogenase complex, which participates in the catabolism of branched-chain amino acids. Draw the reaction product when the following substrate is acted on by the branched-chain a-keto acid dehydrogenase complex.arrow_forwardChemistry Dimethylphenyl-oxopropanoate decarboxylase catalyzes the following reaction. Draw the structure of the cofactor used by this enzyme and propose a mechanism for this reaction.arrow_forwardThe conversion of L-proline to D-proline is shown. The reaction below shows an enzyme-catalyzed reaction that converts from an L amino acid to D amino acid. What type of enzyme catalyzes this reaction? H H+ COOH L-Proline Isomerase Hydrolase Ligase Transferase COOH Transition state H Xco N COOH H D-Prolinearrow_forward
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