Hyaluronic acid (HA), a polymer of about 25 000

Chapter 20, Problem 35CI

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Hyaluronic acid (HA), a polymer of about 25 000 disaccharide units, is a natural component of eye and joint fluid, as well as of skin and cartilage. Due to the ability of HA to absorb water, it is used in skin care products and injections to smooth wrinkles, and for treatment of arthritis. The disaccharide units in HA consist of D-gluconic acid and N-acetyl-D-glucosamine. D-Glucosamine has an amino group (— NH2) in place of the hydroxyl group on carbon 2 of D-glucose. N-acetyl-D-glucos-amine is the amide formed from acetic acid and D-glucosamine. Another natural polymer called chitin is found in the shells of lobsters and crabs. Chitin is made of repeating units of N-acetyl-D-glucosamine connected by ?-1,4-glycosidic bonds. (13.4, 15.3, 15.5, 15.6, 18.4)a. Draw the Haworth structure for the product of the oxidation reaction of the hydroxyl group on carbon 6 in ?-D-glucose to form ?-D-gluconic acid.________________b. Draw the Haworth structure for ?-D-glucosamine.________________c. Draw the Haworth structure for Af-aœtyl-beta-D-glucosamine.________________d. What are the two types of glycosidic bonds that link the monosaccharides in hyaluronic acid?________________e. Draw the structure for a section of chitin with two N-acetyl-beta-D-glucosamine units linked by ?-1,4-glycosidic bonds. The shells of crabs and lobsters contain chitin.