NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY DEPARTMENT OF BIOTECHNOLOGY Professor Bjørn E. Christensen, Department of Biotechnology

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1 Page 1 NRWEGIAN UNIVERSITY F SCIENCE AND TECNLGY DEPARTMENT F BITECNLGY Professor Bjørn E. Christensen, Department of Biotechnology Contact during the exam: phone: , EXAM TBT4135 BIPLYMERS 16 December 2010 Time: Aides: B1. Approved calculator with empty memory, according to list provided by NTNU, is permitted. No printed or written documents may be used during exam. Censoring deadline: 16 January 2011 Censoring: Relative weights of questions: See Appendix 2

2 Page 2 Question 1. a) Describe the chemical structure of cellulose (including aworth formulae) b) Explain briefly the concept ʻdiequatorialʼ linkages c) Which glycosidic linkages in cellulose are diequatorial? d) Explain briefly the chemical basis for production of carboxymethyl cellulose (CMC) (reactants, conditions, mechanism)? e) Cellulose and CMC have different physical properties. Which is the most important? f) The average pk a of CMC is 4.4, whereas the average pk a of a chitosan is 6.0. In which p range can chitosan and CMC in principle form a polyelectrolyte complex (oppositely charged polymers)? Brief explanation. Question 2. The data below shows of the radius of gyration (R G ) and the molecular weight (M w ) for three different biopolymers (A-C) in solution. The data refer to a p of 7.0, room temperature, and an ionic strength (I) of 0.1 M ! " # $ % &'(''' )*+& ),+' -+',''('''.,+' /)+0,/+* 0''(''','0+' 0&+* &)+' a) What is the shape of each of the biopolymers? b) Comment difference in R G -M data between B and C c) B is a polysaccharide containing sulphate groups (one sulphate per 2 sugars on average). ow would R G -M data change (qualitatively) if the

3 Page 3 values were determined at a higher ionic strength (e.g. in 1 M instead of 0.1 M)? d) Define the ionic strength (I) and calculate I for 0.1 M MgCl 2. e) B forms a thermoreversible gel in the presence of K + (potassium) ions. Which polysaccharide can it be? (Name) Question 3. Two proteins (A and B) are both biologically active at 37 C. They both contain several α-helices, which in each case are organised into a well-defined tertiary structure (not the same for A and B). Protein A looses activity upon heating, whereas B looses activity upon cooling. a) Describe briefly the main properties of α-helices in proteins b) What is the thermodynamic explanation for the behaviour of A and B, respectively? c) Can the differences in behaviour be explained in terms of the primary structure? Explain briefly. d) Analysis of the genes in an animal tissue revealed the amino acid sequence of the corresponding protein which given in Appendix 1. Which type of protein is it (most probably)? Brief explanation. e) Are there any ʻanalogiesʼ to the behaviour of protein B among the polysaccharides, for example related to solubility?

4 Page 4 Question 4. Identify the monosaccharides (a-c) and the polysaccharide (d). For monosaccharides, include also the D/L and the anomeric configuration (α/β): a) C b) c) C C 2 d) CNa N C C 3 n

5 Page 5 Question 5. a) Some alginates form strong, elastic gels when Ca ++ ions are added. Which types of alginates form the strongest gels, and what is the mechanism of gelation? b) Alginates can be degraded (depolymerized) by several mechanisms. Explain the chemical principles of one of the mechanisms. c) Assume a sodium (Na + ) alginate is randomly degraded from M w = to g/mol in 60 min. ow long time will it take to degrade from to g/mol? d) Estimate DP n of the alginate when M w is g/mol. e) What is the relative content (weight fraction) of alginate oligomers with DP = 10 in the reaction mixture when M w has reached g/mol?

Page 6 APPENDIX 1: Amino acid abbreviations: Amino acid Three letter code ne letter code alanine ala A arginine arg R asparagine asn N aspartic acid asp D asparagine or aspartic acid asx B cysteine

6 Page 6 APPENDIX 1: Amino acid abbreviations: Amino acid Three letter code ne letter code alanine ala A arginine arg R asparagine asn N aspartic acid asp D asparagine or aspartic acid asx B cysteine cys C glutamic acid glu E glutamine gln Q glutamine or glutamic acid glx Z glycine gly G histidine his isoleucine ile I leucine leu L lysine lys K methionine met M phenylalanine phe F proline pro P serine ser S threonine thr T tryptophan try W tyrosine tyr Y valine val V

7 Page 7 Appendix 2 1a 4 1b 4 1c 3 1d 3 1e 3 1f 3 2a 12 2b 4 2b 4 2c 4 2e 3 3a 6 3b 4 3c 3 3d 3 3e 3 4a 3 4b 3 4c 3 4d 4 5a 4 5b 4 5c 6 5d 3 5e 4 Sum 100

11 questions for a total of 120 points

Your Name: BYS 201, Final Exam, May 3, 2010 11 questions for a total of 120 points 1. 25 points Take a close look at these tables of amino acids. Some of them are hydrophilic, some hydrophobic, some positive