Ligand binding to the haem-copper binuclear catalytic site of cytochrome bo, a respiratory quinol oxidase from Escherichia coli
| Autor: | John C. Salerno, Janet Horrocks, W. John Ingledew |
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| Rok vydání: | 1993 |
| Předmět: |
Anions
Enzyme complex Azides Cytochrome Formates Stereochemistry Cyanide Haem peroxidase Heme Sulfides Ligands Biochemistry Cofactor chemistry.chemical_compound Fluorides Escherichia coli Oxidase test Binding Sites Cyanides biology Cytochrome b Escherichia coli Proteins Electron Spin Resonance Spectroscopy Cytochrome b Group chemistry Spectrophotometry biology.protein Cytochromes Azide Oxidoreductases Copper |
| Zdroj: | European journal of biochemistry. 212(3) |
| ISSN: | 0014-2956 |
| Popis: | The Escherichiu coEi quinol oxidase, cytochrome bo, is closely related to the cytochrome-c oxidase, cytochrome au3 and reacts with ligands to the high-spin ferric haem or the high-spin ferriccupric binuclear catalytic site in similar ways. Cyanide reacts with the isolated enzyme to give a low-spin complex, manifested by a red shift in the Soret band, the loss of an absorption band at 630 nm and the appearance of a low-spin ferric haem EPR resonance at g = 3.3. Sulphide also elicits a low-spin complex, whereas azide gives a mixture of low-spin and high-spin species. Formate and fluoride (and azide) give a blue shift in the Soret band and the development of a modified absorption band in the 600-650 nm range. These latter species are attributed to an integral spin compound involving the binuclear centre. The Escherichia coli respiratory quinol oxidase, cytochrome bo, is one of two membrane-bound terminal respiratory oxidases that the bacterium can express. The other, expressed predominantly under conditions of low 0, tension, is cytochrome bd [l]. Cytochrome bo has been purified and the genes coding for it have been cloned and sequenced. The purified enzyme is comprised of four subunits, although the operon contains five open reading frames [2-41. The enzyme complex contains a low-spin haem, a high-spin haem and a copper centre (Cu,) as prosthetic groups, all located in subunit I. The high-spin haem and the copper form a binuclear (Cu-Fe) site which is the catalytic core of the |
| Databáze: | OpenAIRE |
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