Isoleucine

Isoleucine is a hydrophobic neutral amino acid, the reason why it is hydrophobic is because it has an aliphatic side chain. Due to this hydrophobic characteristic of the amino acid, it interacts more favourably with other aliphatic residues, such as: alanine, valine and leucine, and other non-polar amino acids. This is one of the main factors in stabilizing the folded conformations of proteins[1]. Isoleucine has an additional chiral centre at carbon 3[2][3].