| Autor: |
Pfitzner, Ute, Kirichenko, Anna, Konstantinov, Alexander A., Mertens, Martina, Wittershagen, Axel, Kolbesen, Bernd O., Steffens, Guy C.M., Harrenga, Axel, Michel, Hartmut, Ludwig, Bernd |
| Zdroj: |
FEBS Letters; January 1999, Vol. 456 Issue: 3 p365-369, 5p |
| Abstrakt: |
Recent structure determinations suggested a new binding site for a non-redox active metal ion in subunit I of cytochrome coxidase both of mitochondrial and of bacterial origin. We analyzed the relevant metal composition of the bovine and the Paracoccus denitrificansenzyme and of bacterial site-directed mutants in several residues presumably liganding this ion. Unlike the mitochondrial enzyme where a low, substoichiometric content of Ca 2+was found, the bacterial wild-type (WT) oxidase showed a stoichiometry of one Ca per enzyme monomer. Mutants in Asp-477 (in immediate vicinity of this site) were clearly diminished in their Ca content and the isolated mutant enzyme revealed a spectral shift in the heme avisible absorption upon Ca addition, which was reversed by Na ions. This spectral behavior, largely comparable to that of the mitochondrial enzyme, was not observed for the bacterial WT oxidase. Further structure refinement revealed a tightly bound water molecule as an additional Ca 2+ligand. |
| Databáze: |
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