Question

Why is Alanine to threonine mutation will drastically change protein structure/function than Isoleucine to leucine mutation?

Give clear explanation.

Answer 1

Alanine to threonine mutation will drastically change protein structure/function than Isoleucine to leucine mutation because alanine is a non-polar amino acid and threonine is a polar amino acid. Non-polar amino acids are hydrophobic in nature and are usually found deep inside the protein core Whereas the polar amino acids can be present on the surface. Since polar and non-polar amino acids are present at different locations in a protein hence their replacement with each other would alter the protein structure/function.

Isoleucine and leucine both are non-polar amino acids with not much difference in the R group will not have drastic effect if a mutation changes isoleucine with leucine.