Chapter 9

Draw Haworth projections for the following: (a) O=CC(O)C(O)C(O)CO in \(\alpha\)-furanose form. Name the sugar. (b) The L isomer of (a) (c) \(\alpha\)-D-GleNAc (d) \(\alpha\)-D-Fructofuranose

\(\alpha\)-D-Galactopyranose rotates the plane of polarized light, but the product of its reduction with sodium borohydride (galactitol) does not. Explain the difference.

Why is a type \(\mathrm{O}\) individual considered a universal blood donor? Why is a type \(\mathrm{AB}\) individual considered a universal acceptor?

Dextrans are polysaccharides produced by certain species of bacteria. They are glucans, with primarily \(\alpha(1 \rightarrow 6)\) linkages and with frequent \(\alpha(1 \rightarrow 3)\) branching. Draw a Haworth projection of a portion of a dextran, including one \((1 \rightarrow 3)\) branch point.

What is the natural polysaccharide whose repeating structure can be symbolized by GlcUA \(\beta(1 \rightarrow 3)\) GlcNAc, with these units connected by \(\beta(1 \rightarrow 4)\) links?

The reagent periodate \(\left(\mathrm{IO}_{4}^{-}\right)\)oxidatively cleaves the carbon-carbon bonds between two adjacent carbons carrying hydroxyl groups. Explain how periodate oxidation might be used to distinguish between methyl glycosides of glucose in the pyranose and furanose forms.

Why do you suppose that the influenza virus protein that binds the virus to an infected cell is called hemagglutinin? Hemagglutination is the clumping together of red blood cells.

The diversity of functional groups on sugars that can form glycosidic bonds greatly increases the information content of glycans relative to oligopeptides. Consider three amino acids, A, B, and C. How many tripeptides can be formed from one molecule of each amino acid? Now consider three sugars- glucose, glucuronic acid, and \(N\)-acetylglucosamine. Use shorthand (e.g., Glca \((1 \rightarrow 4)\) GlcUA \(\beta(1 \rightarrow 4)\) GlcNAc to represent 10 trisaccharides with the sequence Glc-GlcUA-GluNAc. Is your list exhaustive?

Are mannose and galactose epimers? Allose and altrose? Gulose and talose? Ribose and arabinose? Consider only D-sugars. Explain your answers.

Explain in about one sentence why it is important to animals for the major carbohydrate storage polymer, glycogen, to be branched rather than unbranched.

Consider the dextran sucrase reaction. Why do you suppose there is not an ATP requirement to energetically drive the creation of glycosidic bonds in the dextran product?

Indicate whether each of the following disaccharides is a reducing (R) or nonreducing (NR) sugar by the criterion of reaction with Fehling's solution. (a) Glco(1 \(\rightarrow 2)\) Fruc \(\beta\) (b) \(\mathrm{Gal} \beta(1 \rightarrow 4) \mathrm{Glc}\) (c) Glca(1 \(\rightarrow\) 1)Glc \(\alpha\) (d) Glcax \((1 \rightarrow 4)\) Gle (e) \(\mathrm{Glc} \beta(1 \rightarrow 6) \mathrm{Glc}\)

Briefly describe the function of uridine triphosphate (UTP) in carbohydrate metabolism.

Explain how oseltamivir (Tamiflu) interferes with influenza virus replication.

Why is a person with type \(\mathrm{AB}\) blood able to receive a blood transfusion from a donor with any of the major blood types (A, B, AB, and \(O\) ) but is able to donate blood only to another type \(\mathrm{AB}\) individual?