G. Buse et al., Evidence for a copper-coordinated histidine-tyrosine cross-link in the active site of cytochrome oxidase, PROTEIN SCI, 8(5), 1999, pp. 985-990
Following hints from X-ray data (Ostermeier C et al., 1997, Pi-oc Natl Acad
Sci USA 94:10547-10553; Yoshikawa S et al., 1998, Science 280:1723-1729),
chemical evidence is presented from four distantly related cytochrome-e oxi
dases for the existence of a copper(B)-coordinated His240-Tyr244) cross-lin
k at the O-2-activating Heme Fea(3)-Cu-B center in the catalytic subunit I
of the enzyme. The early evolutionary invention of this unusual structure m
ay have prevented demaging (OH)-O-.-radical release at e(-)-transfer to dio
xygen and thus have enabled O-2 respiration.