Chemically Modified Amino Acids in Copper Proteins That Bind or Activate Dioxygen

Changing mechanisms: More than half of the known classes of copper oxidase contain a chemically modified amino acid within their active site. Recent experiments by Klinman et al. on the biogenesis of one of these, topaquinone (TPQ; see scheme), have shown that this occurs by a different mechanism from that observed for the aqueous aerobic synthesis of hydroxybenzoquinones in vitro.