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Unformatted text preview: NAME_____________________________ T.A.name & sect.no._________________________ Page 1 Biochemistry 462a -- Problem Set #10 ANSWERS November 9, 2007 (due November 16, 2007); READING chapters 6, 7 15 points 1. (2 pts) Draw the Haworth projection formula of D-glucopyranose. How many different disaccharides (interconvertible or not) could be made with D-glucopyranose? Explain. Answer: (structure of D-glucopyranose in Fig. 7-6 and 7-7, pp. 242-243 of textbook) 19 different disaccharides are possible containing only D-glucopyranose. Explanation: All the 2,3,4, and 6 linkages to second sugar (4 compounds) These could be alpha or beta on sugar #1, (4 x 2 = 8 total compounds) SECOND sugar can be either or (except for the 1 1 linkages) (8 x 2 = 16 total cpds) Three 1 1 linkages ( , , or : 3 more compounds) = 19 disaccharides total 2. (1 pt) Draw the disaccharide unit of chondroitin 4-sulfate and name the constituent monosaccharides . Calculate the net charge of a chondroitin 4-sulfate molecule containing 40 disaccharide units at physiological pH. See figure on p. 253 of textbook: disaccharide of D-glucuronate and N-acetyl- D-galactosamine-4-sulfate. Charge would be 80 because of COO on GlcA, and SO 4 on GalNAc4S of each disaccharide unit 3. (2 pts) Deduce the structure of a disaccharide from the following information and find its NAME in your textbook or notes. Explain how you deduced the structure . Complete hydrolysis yields only D-glucose. It is hydrolyzed by -glucosidase but not by -glucosidase. It does not reduce Cu 2+ to Cu + . (Incidentally, this disaccharide is the "blood sugar" found in the hemolymph of most insects; it has been suggested that it may act as a natural cryoprotectant, the polyhydroxy compound preventing damage to insect tissues from freezing and thawing.) Reasoning :...
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