Question

5. D-sorbital is found in 'sugar-free' chewing gum. It is formed by reducing D-glucose with NaBH Draw the structure of D-sorbital. s. (4 pts) Classify the following amino acid as polar, non- polar, acidic, or basic: 6 (4 pts) The amino acid threonine (thr) has two chiral carbons. Draw a Fischer projection of the 2S,3S configuration of threonine. キ 7.(11 pts) Draw the tripeptide lys-asp-ser at physiological pH 8. (8 pts) The pK, values for aspartic acid are 2.10, 9.82 and 3.86. Draw the structure of aspartic acid at pH 1 low pH, very acidic) and label the acidic protons with the appropriate pKa values. Then calculate the isoelectric point b. (3 pts). At physiological pH would you expect aspartic acid to have a positive charge, a net negative charge or be neutral? What direction would it migrate during electrophoresis? 9. Draw the structure of argenine at low pH, clearly showing which nitrogen atom in the side chain is protonatated. Draw resonance forms to show why this nitrogen atom is preferentially protonated

Answer 1

Ans 5 :

To make D-sorbitol out of glucose , the aldehydic group of glucose is reduced to the hydroxyl group. The formula of the sugar is C₆H₁₄O₆.

The structure of the sugar is shown below ...

CH2OH 2 D-sobifol