Concept explainers
The example of a silyl–Hilbert–Johnson nucleosidation reaction in Section 25.3 is presumed to involve an intermediate ribosyl cation that is stabilized by intramolecular interactions involving the C2 benzoyl group. This intermediate blocks attack by the heterocyclic base from the
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- Draw the dinucleotide dApdG (shown above). Draw a dinucleotide that you would expect to hydrogen bond most stably to dApdG. Include every atom and every ring atom number, every charge, correct orientation of the base and the backbone linkages with respect to the ribose ring, the number of angstroms between N’s and O’s involved in the hydrogen bonds, and the number of angstroms between the riboses involved as support for each base in the hydrogen bonded pair.arrow_forwardThe enzyme that catalyzes the C-Cg bond cleavage reaction that converts serine to glycine removes the substituent (R) bonded to the a-carbon in the first step of the reaction. Starting with PLP bound to serine in an imine linkage, propose a mechanism for this reaction. (Hint: The first step involves removal of the proton from serine's OH group.)arrow_forwardUnder acidic conditions (catalytic amount of acid) in anhydrous methanol, D-galactose can be converted to the methyl galactopyranoside X on the right side of the reaction arrow. Write a detailed mechanism for the reaction. OH H+ HO HO `Me MeOH HO 'OH HO "OH OH OH Xarrow_forward
- Please give the resulting product of the reaction between ribose sugar and the fluorinated pyrimidine (denoted by a starred reactive nitrogen). What type of starting sugar is this ? α (Alpha) or β (beta)arrow_forwardResearchers analysed a glycopeptide (a peptide carrying one or several oligosaccharide groups) and determined both the sequence of the peptide and the sequence of the sugar molecule. The latter was identified as a diholoside coupled to the peptide by an osidic bond. The systematic name of this sugar is: B-D-glucopyranosyl-(1→4)-ß-D-galactopyranose. : Represent the chemical formula of this diholoside in a way that all oses are Question 1 represented according to the Haworth convention. Apart from the furane and/or pyrane cycles all atoms of this molecule must be given.arrow_forwardDraw a diagram of the linear and ring structures of ribose. Show the biochemical mechanism of cyclization of each and name the resultant ring – including the ring type & anomeric carbon designation. Draw and name an amine version, reduced version, and oxidized version, either in ring or Fisher projection.arrow_forward
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- Show the steps and products of the Haworth Projection structure of the following saccharides. The males have to work on the naturally occurring form of D-ribose and the females are the structure of D-mannose. Expanded structure of the given molecule Fischer Projection HAWORTH PROJECTIONarrow_forwardA Cu² reagent called Benedict's reagent in the presence of a base is commonly used to oxidize an aldose to the aldonic acid. Carbohydrates that are oxidized with Benedict's reagent are called reducing sugars because the Cu (blue color) in Benedict's reagent is reduced to Cu (brick-red) during the reaction. What product is formed when D-sorbose is treated with Benedict's reagent? Change the structure in the drawing area to show the aldonic acid product formed if the compound is easily oxidized. If there are no changes to be made, check the No changes box under the drawing area. H- HO- H- CH₂OH C=0 OH -H OH CH₂OH X 0:0 #arrow_forwardIf lactose is first hydrolyzed (by addition of sulfuric acid) into its constituent monosaccharide, and then subjected to complete methylation, what methylated products do you expect?arrow_forward
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