Organic Chemistry (8th Edition)
8th Edition
ISBN: 9780134042282
Author: Paula Yurkanis Bruice
Publisher: PEARSON
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Chapter 22.13, Problem 28P
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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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?
4. The AGo for the aldolase reaction is 22.8 kJ/mol. When the reaction is run in a hepatocyte cell at
37°C, the concentrations of the intermediates are: fructose 1,6-bisphosphate =1.41 x 103 M,
glyceraldehyde 3-phosphate 2.95 x 10-6 M, and dihydroxyacetone phosphate = 1.62 x 10-5 M.
Calculate the free energy change for this reaction
Is this reaction thermodynamically favorable
TPP is a coenzyme for transketolase, the enzyme that catalyzes the conversion of a ketopentose (xylulose5-phosphate) and an aldopentose (ribose-5-phosphate) to an aldotriose (glyceraldehyde-3-phosphate) and a ketoheptose (sedoheptulose-7-phosphate). Notice that the total number of carbons in the reactants and products is the same (5 + 5 = 3 + 7). Propose a mechanism for this reaction.
Chapter 22 Solutions
Organic Chemistry (8th Edition)
Ch. 22.2 - Compare each of the mechanisms listed here with...Ch. 22.2 - Prob. 3PCh. 22.2 - Prob. 4PCh. 22.3 - a. Draw the mechanism for the following reaction...Ch. 22.5 - Prob. 7PCh. 22.5 - Propose a mechanism for the Co2+ catalyzed...Ch. 22.6 - Prob. 9PCh. 22.7 - Prob. 10PCh. 22.7 - Prob. 12PCh. 22.7 - Prob. 13P
Ch. 22.9 - Which of the following amino acid side chains can...Ch. 22.9 - Which of the following C-terminal peptide bonds is...Ch. 22.9 - Carboxypeptidase A has esterase activity as well...Ch. 22.10 - Arginine and lysine side chains fit into trypsins...Ch. 22.10 - Explain why serine proteases do not catalyze...Ch. 22.11 - If H2 18O is used in the hydrolysis reaction...Ch. 22.11 - Draw the pH-activity profile for an enzyme that...Ch. 22.12 - The pHactivity profile for glucose-6-phosphate...Ch. 22.12 - Prob. 23PCh. 22.13 - Draw the mechanism for the hydroxide ion-catalyzed...Ch. 22.13 - What advantage does the enzyme gain by forming an...Ch. 22.13 - Prob. 26PCh. 22.13 - Prob. 27PCh. 22.13 - Aldolase shows no activity if it is incubated with...Ch. 22 - Which of the following parameters would be...Ch. 22 - Prob. 29PCh. 22 - Prob. 30PCh. 22 - Prob. 31PCh. 22 - Indicate the type of catalysis that is occurring...Ch. 22 - The deuterium kinetic isotope effect (KH2O/KD2O)...Ch. 22 - Prob. 34PCh. 22 - Co2+ catalyzes the hydrolysis of the lactam shown...Ch. 22 - there are two kinds of aldolases. Class I...Ch. 22 - Prob. 37PCh. 22 - The hydrolysis of the ester shown here is...Ch. 22 - Prob. 39PCh. 22 - At pH = 12, the rate of hydrolysis of ester A is...Ch. 22 - 2-Acetoxycyclohexyl tosylate reacts with acetate...Ch. 22 - Proof that an imine was formed between aldolase...Ch. 22 - Prob. 43PCh. 22 - a. Explain why the alkyl halide shown here reacts...Ch. 22 - Triosephosphate isomerase (TIM) catalyzes the...
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- One 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_forwardIn the glycolytic pathway, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to form two three-carbon sugars, which undergo further metabolism . In this pathway, an isomerization of glucose 6-phosphate tofructose 6-phosphate (shown below) occurs two steps before the cleavage reaction (the intervening step is phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate ). What does the isomerization step accomplish from a chemical perspective? (Hint: Consider what might happen if the C—C bond cleavage were to proceed without the preceding isomerization.)arrow_forwardTPP is a coenzyme for transketolase, the enzyme that catalyzes the conversion of a ketopentose (xylulose- 5-phosphate) and an aldopentose (ribose-5-phosphate) to an aldotriose (glyceraldehyde-3-phosphate) anda ketoheptose (sedoheptulose-7-phosphate). Notice that the total number of carbons in the reactants and products is the same (5 + 5 = 3 + 7). Propose a mechanism for this reaction.arrow_forward
- Imidazoleglycerol‑phosphate dehydratase is an enzyme in the histine biosynthesis pathway. It catalyzes the E1 dehydration of D‑erthyro‑imidazole‑glycerol phosphate to imidazole acetol‑phosphate. This is a rare example of a biological E1 reaction, as most biological elimination reactions occur through E1cB instead. In this reaction, D‑erthyro‑imidazole‑glycerol phosphate is first protonated to form a good leaving group. Then, the leaving group is ejected to form the resonance‑stabilized carbocation shown. Draw curved arrows forming the most stable resonance structure to explain why this reaction goes through an E1 mechanism. Draw curved arrows to form the most stable resonance structure.arrow_forwardIf an enzyme-catalyzed reaction has a high rate at low pH and low rate at higher pH, this implies that a group on either the enzyme or the substrate must be for an efficient reaction. leaving group oxidoreductase coenzymes O protonated deprotonated The compound that consists of deoxyribose linked by an N-glycosidic bond to N-9 of guanine is: adenylate deoxyguanosine guanosine nucleotide guanylatearrow_forwarda Lactate dehydrogenase H H3C-C-coO- ОН ooc-C-CH3 L-(+)-Lactase Pyruvate This is a(an) b Creatine kinase CH3 O CH3 O H2N, АТР ADP NH2 NH2 Adenosine triphosphate Adenosine diphosphate Creatine Phosphocreatine This is a(an)arrow_forward
- 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.…arrow_forwardWhich of the following enzymes catalyzes a reaction with the pictured compound as an intermediate? = Hz C—6 ཆོས་རིག་ག་ག་ག་ག་ག་གས་པ་ 0—P, O succinyl-CoA synthetase fumarase succinate dehydrogenase malate dehydrogenase a-ketoglutarate dehydrogenasearrow_forwardThe rate-limiting step is a metabolic pathway is the slowest step which determines the overall rate of the other reactions in the pathway. In glycolysis, the rate limiting step is a phosphorylation reaction where phosphofructokinase (PFK-1) catalyzes the reaction fructose-6-bisphosphate -> fructose-1,6-bisphosphate, the same step in gluconeogenesis. Select one: The statement is FALSE. The statement is TRUE.arrow_forward
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