Question

Consider the following amino acids for questions 11-13. Choose the best answers. cysteine serine lysine phenylalanine aspartate Which amino acid's R group has a pKa nearest physiological pH? Which amino acid would you most expect to find in the centre of a folded globular protein? Which amino amino acid can be phosphorylated? The overall charge on the peptide (G-R-A-M-P-S) at pH 12.5 is: -1 -0.5 -1.5 +0.5 1 15. What term best describes the protein secondary structure element drawn below: coiled coil Alpha helix anti-parallel Beta sheet parallel Beta sheet a poly-proline helix Why is the peptide bond planar? Bulky side chains prevent free rotation around the bond. It contains partial double-bond character, preventing rotation. Hydrogen bonding between the NH and C=0 groups limits movement. None of the above. All of the above. The following protein is embedded In a vacuolar membrane, where it functions as a channel. Consider the features of this protein for questions 17-19: If one Beta-strand is comprised of eight amino acids, how long is it, in Angstroms? 56 48 28 12 None of the above Consider the necessary biochemical features of a single Beta strand of this protein. Which sequence is most likely from a beta strand in this protein? GSAKLR GALSKR GASKRL GRKSAL Cannot tell If this protein is 345 amino acids long, estimate its molecular weight. 34 kDa 38 kDa 34000kDa 38000kDa A metric femtotonne.

Answer 1

Consider the following amino acids for questions 11-13. Choose the best answers A) cysteine B) serine 13 C) lysine D) phenylalanine E) aspartate 8.3 11. Which amino acid's R group has a pKa nearest physiological pH? Cysteine 3.9 pKa values of R group A gseineB) serine0D phenylalanine E aspartate C) lysine D) phenylalanine E) aspartate 8.3 13 0.8 3.9 of amino acids Thus, cysteine (8.3) has a side chain with pKa nearest to the physiological pH (7.4) 12. Which amino acid would you most expect to find in the centre of a folded globular protein? The interior of the folded globular protein contains hydrpphobic or non-polar amino acids. Phenyl alanine is a non-polar amino acid, which is likely to present in the interior of the folded protein. 13. Which amino amino acid can be phosphorylated? Serine is most likely to be phsophorylated as it contains hydroxyl group in its side chain.