Hydroxylysine

 ( Alpha-amino Acids ) 

Hydroxylysine ( Hyl) is an amino acid with the molecular formula C₆H₁₄N₂O₃. It was first discovered in 1921 by Donald Van Slyke as the 5-hydroxylysine form. It arises from a post-translational Hydroxyl modification of lysine. It is most widely known as a component of collagen. Hydroxylysine at University of Oulu

It is biosynthesized from lysine via oxidation by lysyl hydroxylase enzymes. The most common form is the (5 R) stereoisomer found in collagen. However, the enzyme JMJD6 has recently been shown to be a lysyl hydroxylase which modifies an RNA splicing factor producing the (5 S) stereoisomer. Additionally, in E. coli, there has been at least one lysine N-hydroxylase enzyme identified, named IucD.