Examine the three sequences below for collagen-like proteins.If hydrogen bonding were the most important feature in determining strength in fibrous proteins,which of the following sequences likely has the highest melting temperature and why? (Note: Flp = fluoroproline;Hyp = hydroxyproline)
(I)Pro-Hyp-Gly-Pro-Hyp-Gly-Pro-Hyp-Gly
(II)Pro-Flp-Gly-Pro-Flp-Gly-Pro-Flp-Gly
(III)Gly-Pro-Thr-Gly-Pro-Thr-Gly-Pro-Thr
A)"1" because Hyp has OH groups
B)"1" because the electronegativity of oxygen is greater
C)"2" because the electronegativity of proline is greater
D)"2" because the electronegativity of the -OH group increases hydrogen bond strength
E)"3" because Thr is a small amino acid which allows close packing

Question

Quizplus · Accepted Answer

Hydroxyproline (Hyp) has OH groups that can form hydrogen bonds with other groups in the sequence, increasing stability and ultimately increasing the melting temperature. Both sequences I and II contain Hyp, but sequence I has more Hyp residues, making it more likely to have a higher melting temperature due to more potential hydrogen bonding interactions. Sequence III does not contain any Hyp residues, making it less likely to have a high melting temperature based on hydrogen bonding alone. The electronegativity of oxygen and proline and the size of threonine do not significantly affect hydrogen bonding strength in this context.

Examine the Three Sequences Below for Collagen-Like Proteins