Question

True or false?

The zwitterionic form of glutamine predominates in the pH range of 1.0-2.0.
True False  Prion diseases such as Scrapie, Creutzfeldt-Jakob, and Mad Cow diseases occur when normal beta-sheet-rich prion proteins are converted to alpha helix-rich, insoluble protein fibers.
True False  Hydrogen bonds between carbonyl oxygens and hydrogen atoms covalently bonded to carbons in adjacent peptides contribute to the stabilization of β-sheets.
True False  Poly glutamate is unlikely to form an alpha helix in solution at pH 7.5.
True False  When the alpha-carboxyl group of one amino acid and the alpha-amino group of another amino acid are joined in a peptide bond, the amino and carboxyl groups will no longer ionize.
True False  Basic proteins have a higher proportion of amino acids that are protonated at around neutral pH than acidic proteins.
True False  The flexibility of a polypeptide chain is due to free rotation about its peptide bonds.

Answer 1

1. False - zwitterionic form of glutamine in 5.65

2. False - Prion proteins converted ftom alpha helix-rich to beta sheet rich protein for causes disease.

3. False

4. True - It correctly folded when its side chains are neutral. For glutamate pKR value for side chain is 4.25. So pH of solution is cross this value to 7.5. So it attains -ve charge by removing H+ ion from COOH.

5. True

6. True. Basic proteins Lys, Arg, His pK1-2 PkR-10, Pk2-8. AT neutral pH 7 only COOH releases its H+ ions other Amino acids except His has NH3+ in its state.

7. False - Each peptide bond has some double-bond character due to resonance and cannot rotate.