Concept explainers
Interpretation:
Given that galactose is
Concept introduction:
UDP-Galactose has an axial –OH on C4 while UDP-glucose has it in equatorial position. The isomerization of UDP-galactose to UDP-glucose can be brought about by oxidizing the -OH on C4 in to a
To propose:
A mechanism for the isomerization of UDP-galactose to UDP-glucose where UDP is uridylyl diphosphate. The enzyme responsible for the transformation uses NAD+ as cofactor.
Want to see the full answer?
Check out a sample textbook solutionChapter 17 Solutions
Organic Chemistry
- Propose a mechanism for the biosynthesis of the sesquiterpenoid trichodiene from farnesyl diphosphate. The process involves cyclization to give an intermediate secondary carbocation, followed by several carbocation rearrangements.arrow_forwardNaturally occurring compounds called terpenoids, which we'll discuss in Section 27-5, are biosynthesized by a pathway that involves loss of CO2 from 3-phosphomevalonate 5-diphosphate to yield isopentenyl diphosphate. Use curved arrows to show the mechanism of this reaction.arrow_forwardIn dilute aqueous base, (R)-glyceraldehyde is converted into an equilibrium mixture of (R,S)-glyceraldehyde and dihydroxyacetone. Propose a mechanism for this isomerization.arrow_forward
- Naturally occurring compounds called cyanogenic glycosides, such as lotaustralin, release hydrogen cyanide, HCN, when treated with aqueous acid. The reaction occurs by hydrolysis of the acetal linkage to form a cyanohydrin, which then expels HCN and gives a carbonyl compound. (a) Show the mechanism of the acetal hydrolysis and the structure of the cyanohydrin that results. (b) Propose a mechanism for the loss of HCN, and show the structure of the carbonyl compound that forms.arrow_forwardOne of the later steps in glucose biosynthesis is the isomerization of fructose 6-phosphate to glucose 6-phosphate. Propose a mechanism, using acid or base catalysis as needed.arrow_forwardOne step in the urea cycle for ridding the body of ammonia is the conversion of argininosuccinate to the amino acid arginine plus fumarate. Propose a mechanism for the reaction, and show the structure of arginine.arrow_forward
- One of the steps in the biosynthesis of uridine monophosphate is the reaction of aspartate with carbamoyl phosphate to give carbamoyl aspartate followed by cyclization to form dihydroorotate. Propose mechanisms for both steps.arrow_forwardDihydropyran is synthesized by treating tetrahydrofurfuryl alcohol with an arenesulfonic acid, ArSO3H. Propose a mechanism for this conversion.arrow_forwardThe first step in the metabolism of glycerol, formed by digestion of fats, is phosphorylation of the pro-R—CH2OH group by reaction with adenosine triphosphate (ATP) to give the corresponding glycerol phosphate plus adenosine diphosphate (ADP). Show the stereochemistry of the product.arrow_forward
- Amino acids can be prepared by reaction of alkyl halides with diethyl acetamidomalonate, followed by heating the initial alkylation product with aqueous HCl. Show how you would prepare alanine, CH3CH(NH2)CO2H, one of the twenty amino acids found in proteins, and propose a mechanism for acid-catalyzed conversion of the initial alkylation product to the amino acid.arrow_forwardPropose a synthesis pathway and reagents for the preparation of the following compound. (+/-) indicates a racemic connectionarrow_forwardThe rate constant for the uncatalyzed reaction of two molecules of glycine ethyl ester to form glycylglycine ethyl ester is 0.6 M- 1s - 1. In the presence of Co2 +, the rate constant is 1.5 * 106 M- 1s - 1. What rate enhancement does the catalyst provide?arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage LearningIntroduction to General, Organic and BiochemistryChemistryISBN:9781285869759Author:Frederick A. Bettelheim, William H. Brown, Mary K. Campbell, Shawn O. Farrell, Omar TorresPublisher:Cengage Learning