Wikipedia - L-Isoleucine
Isoleucine (abbreviated as Ile or I), encoded by the codons ATT, ATC, ATA, is an -amino acid that is used in the biosynthesis of proteins. It contains an -amino group (which is in the protonated NH+
3 form under biological conditions), an -carboxylic acid group (which is in the deprotonated COO form under biological conditions), and a hydrocarbon side chain, classifying it as a non-polar, uncharged (at physiological pH), aliphatic amino acid. It is essential in humans, meaning the body cannot synthesize it, and must be ingested in our diet.