ASP-193 AND GLU-218 OF SUBUNIT-II ARE INVOLVED IN THE MN2-BINDING OF PARACOCCUS-DENITRIFICANS CYTOCHROME-C-OXIDASE()

Cytochrome c oxidase contains a binding site for a non-redox-active me tal at the interface of submits I and II, usually a magnesium ion, In Paracoccus denitrificans oxidase, typically 20% may be replaced by man ganese, using standard growth media, Site-directed mutants were constr ucted in subunit II (D193N and E218Q), and the isolated enzymes analyz ed by total-reflection X-ray fluorescence spectrometry and EPR, Both m utants show a strong reduction of the manganese stoichiometry and a di minished electron transfer activity, demonstrating that D193 and E218 are involved in the binding of a manganese/magnesium ion in this site. (C) 1997 Federation of European Biochemical Societies.