On the environment of zinc in beef heart cytochrome c oxidase: an x-ray absorption study.

A. Naqui, Linda S Powers, M. Lundeen, A. Constantinescu, B. Chance

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Abstract

The role of zinc in beef heart cytochrome c oxidase has been studied by using x-ray absorption spectroscopy, zinc depletion and secondary structure predictions of subunits of beef heart cytochrome c oxidase. The stoichiometry of zinc in cytochrome oxidase has been determined in 35 different preparations and found to be one-half of copper (Cu:Zu = 2:1). Zinc is tightly bound to this enzyme and cannot be removed by dialysis against EDTA. However, zinc could be partially (up to 50%) depleted by treating the enzyme with either dipicolinic acid or by trypsin digestion. This partial depletion of zinc does not change the O2 uptake rate. X-ray absorption spectroscopy shows that the atom is in a distorted tetrahedral environment with mostly sulfur ligands. Since subunit VIa removed by the digestion removes about one-half the zinc, a possible binding site involves the two S sites present in that subunit with an appropriate folding in a structural role.

Original languageEnglish (US)
Pages (from-to)12342-12345
Number of pages4
JournalJournal of Biological Chemistry
Volume263
Issue number25
Publication statusPublished - Sep 5 1988
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry

Cite this

Naqui, A., Powers, L. S., Lundeen, M., Constantinescu, A., & Chance, B. (1988). On the environment of zinc in beef heart cytochrome c oxidase: an x-ray absorption study. Journal of Biological Chemistry, 263(25), 12342-12345.