In order to understand heme environment of a heme-regulated phosphodiesterase (Ec DOS), the binding behavior of cyanide to the Fe (III) complex was examined. Interestingly, the rate of cyanide binding to full-length Ec DOS was unusually slow with kon = 0.0022mM-1 s-1, while the rate for the isolated heme domain of Ec DOS (0.045mM-1 s-1) was 20-fold higher. Ala and Leu mutations at Met95, which has been suggested to be a heme axial ligand, increased the kon rate 11- and 8-fold, respectively, and dramatically decreased the cyanide dissociation rate from the isolated heme domain. His mutation at Met95, on the other hand, caused a 17-fold decrease in the kon value. We discuss the unusual cyanide binding behavior and the role of Met95 in controlling cyanide binding.
|ジャーナル||Biochemical and biophysical research communications|
|出版ステータス||Published - 2002|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology