L-isoleucine is the L-enantiomer of isoleucine. It has a role as a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite, a plant metabolite, a human metabolite, an algal metabolite and a mouse metabolite. It is an aspartate family amino acid, a proteinogenic amino acid, an isoleucine and a L-alpha-amino acid. It is a conjugate base of a L-isoleucinium. It is a conjugate acid of a L-isoleucinate. It is an enantiomer of a D-isoleucine. It is a tautomer of a L-isoleucine zwitterion.