Auto-hydroxylation of FIH-1: an Fe(II), alpha-ketoglutarate-dependent human hypoxia sensor

HIF-asparaginyl hydroxylase (FIH-1) normally couples O(2)-activation to hydroxylation of Asn(803) on the alpha-subunit of the hypoxia-inducible factor (HIF alpha), a key step in pO(2) sensing; in the absence of HIF alpha, O(2)-activation becomes uncoupled, leading to self-hydroxylation at Trp(296) and a purple Fe(III)-O-Trp chromophore-this alternative reactivity may affect human hypoxia sensing.