Iron (II)/2-oxoglutarate (2-OG)-dependent oxygenases catalyse oxidative reactions in a range of metabolic processes. Proline 3-hydroxylase hydroxylates proline at position 3, the first of a 2-OG oxygenase catalysing oxidation of a free alpha-amino acid. The structure of proline 3-hydroxylase contains the conserved motifs present in other 2-OG oxygenases including a jelly roll strand core and residues binding iron and 2-oxoglutarate, consistent with divergent evolution within the extended family. This family represent the arginine, asparagine and proline hydroxylases. The aspartyl/asparaginyl beta-hydroxylase (EC:1.14.11.16) specifically hydroxylates one aspartic or asparagine residue in certain epidermal growth factor-like domains of a number of proteins [1].

1: A fully active catalytic domain of bovine aspartyl (asparaginyl) beta-hydroxylase expressed in Escherichia coli: characterization and evidence for the identification of an active-site region in vertebrate alpha-ketoglutarate-dependent dioxygenases. Jia S, McGinnis K, VanDusen WJ, Burke CJ, Kuo A, Griffin PR, Sardana MK, Elliston KO, Stern AM, Friedman PA; Proc Natl Acad Sci U S A 1994;91:7227-7231. PMID:8041771