Molecular model of Isoleucine (C6. H13. N. O2), an essential amino acid. Unable to be produced by the body, isoleucine must be sourced from the diet. This amino acid has many roles within the human body. It is best known for its ability to support blood clotting at wound sites and assisting with muscle tissue repair. Isoleucine an also help to boost energy levels and improve stamina. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white), nitrogen (blue) and oxygen. Illustration.