Structure and Reactivity of Multiple Forms of Cytochrome Oxidase As Evaluated by X-ray Absorption Spectroscopy and Kinetics of Cyanide Binding

Ali Naqui, Chellappa Kumar, Britton Chance, Yuan Chin Ching, L. Powers

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

The extended X-ray absorption fine structure (EXAFS) data show differences between the active site structures of different cytochrome oxidase preparations. In the resting (as isolated) state of the Yonetani preparation, the bridging atom between Fe3+ a3 and Cu2+ a3 is present [Powers, L, Chance, B., Ching, Y., & Angiolillo, P. (1981) Biophys. J. 34, 465], whereas in another preparation (e.g., Hartzell-Beinert), this atom seems to be bound only to Fe3+ a3 in a significant fraction of the molecules. Both preparations bind cyanide in a multiphasic fashion, suggesting that the resting cytochrome oxidase is not homogeneous but rather is a mixture of several forms. The proportion of these forms as detected by cyanide binding kinetics differs for different preparations. However, upon reduction and reoxidation (conversion to the “oxygenated” form) the cyanide binding kinetics become monophasic and all preparations of the oxygenated form bind cyanide at the same rate. Thus, a combination of structural and kinetic approaches seems necessary for evaluation of the nature of the active site of cytochrome oxidase in its various forms.

Original languageEnglish (US)
Pages (from-to)6222-6227
Number of pages6
JournalBiochemistry
Volume23
Issue number25
DOIs
StatePublished - Dec 1984
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Structure and Reactivity of Multiple Forms of Cytochrome Oxidase As Evaluated by X-ray Absorption Spectroscopy and Kinetics of Cyanide Binding'. Together they form a unique fingerprint.

Cite this