EBK ORGANIC CHEMISTRY
8th Edition
ISBN: 8220102744127
Author: Bruice
Publisher: PEARSON
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Chapter 23.5, Problem 16P
Explain why the ability of PLP to catalyze an amino acid transformation is greatly reduced if the OH substituent of pyridoxal phosphate is replaced by OCH3.
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Chapter 23 Solutions
EBK ORGANIC CHEMISTRY
Ch. 23.1 - Prob. 2PCh. 23.1 - Prob. 3PCh. 23.2 - How many conjugated double bonds are there in a....Ch. 23.2 - Instead of adding to the 4a position and...Ch. 23.2 - Prob. 7PCh. 23.3 - Prob. 8PCh. 23.3 - Acetolactate synthase is another TPP-requiring...Ch. 23.3 - Acetolactate synthase transfers the acyl group of...Ch. 23.3 - Prob. 12PCh. 23.5 - Which compound is more easily decarboxylated?
Ch. 23.5 - Prob. 14PCh. 23.5 - Explain why the ability of PLP to catalyze an...Ch. 23.5 - Explain why the ability of PLP to catalyze an...Ch. 23.5 - The enzyme that catalyzes the C C bond cleavage...Ch. 23.5 - Propose a mechanism for the ,-elimination reaction...Ch. 23.6 - Ethanolamine ammonia lyase, a coenzyme...Ch. 23.6 - Prob. 20PCh. 23.7 - How do the structure of tetrahydrofolate and...Ch. 23.7 - What is the source of the methyl group in...Ch. 23.8 - Thiols such as ethanethiol and propanethiol can be...Ch. 23 - How does the metal ion in carboxypeptidase A...Ch. 23 - Prob. 24PCh. 23 - Prob. 25PCh. 23 - For each of the following reactions, name both the...Ch. 23 - Prob. 27PCh. 23 - When transaminated, the three branched-chain amino...Ch. 23 - What acyl groups have we seen transferred by...Ch. 23 - Propose a mechanism for the following reaction:Ch. 23 - Draw the products of the following reaction, where...Ch. 23 - When UMP is dissolved in T2O, exchange of T for H...Ch. 23 - Dehydratase is a PLP-requiring enzyme that...Ch. 23 - In addition to the reaction mentioned in Section...Ch. 23 - PLP can catalyze both ,-elimination reactions...Ch. 23 - The glycine cleavage system is a group of four...Ch. 23 - Prob. 37PCh. 23 - FADH2 reduces , -unsaturated thioesters to...
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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_forwardOne of the steps in the pentose phosphate pathway for glucose catabolism is the reaction of xylulose 5-phosphate with ribose 5-phosphate in the presence of a transketolase to give glyceraldehyde 3-phosphate and sedoheptulose 7-phosphate. (a) The first part of the reaction is nucleophilic addition of thiamin diphosphate (TPP) ylide to xylulose 5-phosphate, followed by a retro-aldol cleavage to give glyceraldehyde 3-phosphate and a TPPcontaining enamine. Show the structure of the enamine and the mechanism by which it is formed. (b) The second part of the reaction is addition of the enamine to ribose 5-phosphate followed by loss of TPP ylide to give sedoheptulose 7-phosphate. Show the mechanism.arrow_forwardThe first step in the catabolism of most amino acids is the removal of the nitrogen atom by transfer to an a-keto acid, a reaction catalyzed by an enzyme called a transaminase. The a-keto acid acceptor is often a-ketoglutarate. Modify the structures in the product to show the products of the transamination of cysteine. Be sure to show functional groups with the charge and number of attached hydrogen atoms appropriate for pH 7.4. transaminase + O=C H₂N-CH + CH₂ CH₂ CH₂ SH Incorrect H₂N || CH | CH₂ | CH₂ I || O || n | CH₂ T SHarrow_forward
- 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 histadinearrow_forwardIn bacteria, much of the putrescine is synthesized, not from ornithine but from arginine, which decarboxylates to yield agmatine. Formulate a plausible pathway from arginine to putrescine, using this intermediate.arrow_forwardNonearrow_forward
- (i) Write the product obtained when D-glucose reacts with HCN. (ii) What type of bonding stabilizes the α-helix structure of proteins? (iii) Write the name of the disease caused by the deficiency of vitamin B12arrow_forwardSolve it asaparrow_forwardExplain why the ability of PLP to catalyze an amino acid transformation is greatly reduced if the OH substituent of pyridoxal phosphate is replaced by OCH3.arrow_forward
- 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.arrow_forwardWrite down the reactions: D-Glucopyranose + CH3I →arrow_forwardEsterase is an enzyme that catalyzes the hydrolysis of esters. It hydrolyzes esters of L-amino acids more rapidly than esters of d-amino acids. How can this enzyme be used to separate a racemic mixture of amino acids?arrow_forward
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