What are the most flexible and the most rigid amino acids?
Glycine is most flexible with no side chain. Proline is most rigid, with an imino group instead of amino. 4. Which amino acids have hydroxyl groups? A: Serine, Threonine, and Tyrosine. These are important in hydrogen bonding. 5. Which amino acid can form disulfide bonds? A: Cysteine. The two cysteine residues linked together are called cystine. These bonds can contribute to the strength of a protein. Insulin contains two peptides linked by disulfide bonds. 6. Where would you likely find non-polar amino acids in the structure of a protein? A: They are more likely found in the central core of the enzyme or in trans-membrane segments that associated with the lipid bilayer. 7. Name the acidic amino acids. A: glutamic acid = glutamate, and aspartic acid = aspartate. The pK of these is around 4. That means at pH=4 they are 1/2 negatively charged, 1/2 uncharged. The higher the pH the more charged they will be. Amount charged at given pH is determined by Henderson-Hasselbalch equation: pH=2, 1