Question

Assuming

1.

Amino acid 212 is changed from Glycine to Alanine in warm adapted species.

Amino acid 216 is changed from Glutamine to Lysine in warm adapted species.

Amino acid 219 is changed from Theornine to Alanine in warm adapted species.

Amino acid 220 is changed from Asparatie to Glutamate warm adapted species.

2.

Both Glycine and Alanine are non polar amino acids.

Glutamine is uncharged while lysine is positively charged

Threonine is polar uncharged while Alanine is hydrophobic

Both Asparatie and Glutamate are negatively charged.

3.

The change would likely have no effect as both are non polar and hydrophobic.

There would be change as a uncharged amino acid is being replaced with positively charged.

There would be change as a polar charged amino acid is being replaced with a hydrophobic amino acid.

There would be no effect with this change as both are negatively charged amino acids.

My Question is that: Assuming that the mutations are adaptive, how should the changes that you identified affect the stability of the protein at low and high temperatures?

Answer 1

1. Glycine to alanine both are hydrophobic amino acid present inside of the 3D structure and forms a hydrophobic interaction. So it not affect the any stability of protein present and favour the high temperature environment organism.

2. Glutamine is non charged amino acids mutated  to charged amino acid lysine. Lysine is a positive charge so it try to make a hydrogen bond in cold water or low temperature environment and Asparagine makes hydrogen bonds in warm environment. This mutation adapted both the environment.

3. Theronine is polar charge and Ala is hydrophobic so it alter the protein structure and increase the hydrophobic interaction it advantage for warm environment.

4. Asp to Glu both are negative charge amino acids so no effect on the effect it favors the low temperature due to -ve charge it makes with water and support the low temperature organism from freezing.