1 Which IMF would you expect to be the strongests attraction between each pair?
ID: 873464 • Letter: 1
Question
1 Which IMF would you expect to be the strongests attraction between each pair?
a. serine and asparagine
b. leucine and alanine
c. lysine and aspartate
2. Describe one way that low pH can destabilize a proteins structure.
3. Describe how basic (high) pH can destablize a proetins structure. In your description, include specific details about which amino acids would be affected by a change from neutral pH to basic pH.
4. If you wanted to keep bacteria from growing in your leftover protein sample, you could store it in the fridge until next week. The cold temperature slows down all chemical reaction, including the ones that allow bacteria to grow and multiply. Alternatively, you could boil your sample and keep it covered. The heat would kill any bacteria present and the cover would keep new ones from getting in. If you want to continue investigating the stability of this protein next week, which approach would be best for this sample, and why?
Explanation / Answer
1. Of the three given pairs, c. lysine and aspartate will have the strongest attraction between each pair. This is due to enhanced bonding in the pair by additional amine and carboxylic acid functionality.
2. Changes in pH can influence the extent to which certain amino acid side chains (or the amino and carboxyl termini) are protonated. The result is a change in net charge on the protein, which can lead to electrostatic attractions or repulsions between different regions of the protein. The final effect is a change in the protein's three-dimensional shape or even complete denaturation. Low pH causes protonation of the side chains of Asp, Glu, and His, thus preventing electrostatic interactions.
3. Change in pH causes change in charges a protein holds in its structure. At basic pH, the carboxylic acid functionality will be deprotonated, thus loosing some of the intermolecular forces present withing the system. Let say for example, aspartic acid, will get destabilized at high basic pH.
4. If we want to continue investigating the stabilty of the protein next week, the best approach would be to store it in the fridge until next week. The cold temperature slows down all the chemical reaction without affecting the structure or property of the protein sample. High temerpature such as boiling may alter the structure of the molecule and may also cause denaturation of te protein. Hence boiling is not a good option in this case.
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