Chapter 7

Volume of Chondroitin Sulfate in Solution One critical function of chondroitin sulfate is to act as a lubricant in skeletal joints by creating a gel-like medium that is resilient to friction and shock. This function seems to be related to a distinctive property of chondroitin sulfate: the volume occupied by the molecule is much greater in solution than in the dehydrated solid. Why is the volume so much larger in solution?

Permutations of a Trisaccharide Three different hexoses (A, B, and C) can be combined to form a large number of trisaccharides. What structural features of trisaccharides allow so many permutations and combinations?

Information Content of Oligosaccharides The carbohydrate portion of some glycoproteins may serve as a cellular recognition site. To perform this function, the oligosaccharide(s) must have the potential to exist in a large variety of forms. Which can produce a greater variety of structures: oligopeptides composed of five different amino acid residues, or oligosaccharides composed of five different monosaccharide residues? Explain.

Determination of the Extent of Branching in Amylopectin A biochemist wants to determine the amount of branching in amylopectin, defined by the number of $(\alpha 1\to 6)$ glycosidic bonds present. First, she treats the sample with methyl iodide, a methylating agent that replaces the hydrogen of every sugar hydroxyl with a methyl group, converting $-\mathrm{OH}$ to $-{\mathrm{OCH}}_3$. She then hydrolyzes all the glycosidic bonds in the treated sample in aqueous acid and measures the amount of 2,3 -di- $O$-methylglucose formed.