Ferrochelatase activity inAzospirillum brasilense with reference to the influence of metal cations |
| |
Authors: | Miles J Price Bernadette L Saiz Larry L Barton |
| |
Institution: | (1) Laboratory of Microbial Chemistry, Department of Biology, University of New Mexico, 87131 Albuquerque, NM, USA |
| |
Abstract: | Summary Ferrochelatase in membrane preparations fromAzospirillum brasilense displayed an activity of 2.17 mol protoheme formed · h–1 · mg protein–1 which is 10-fold greater than previous reports for other bacteria. This ferrochelatase showed an apparentK
m of 20.9 M for Fe2+, a pH optimum of 6.0–6.5, and stimulation by oleic or stearic acids. Co2+, Cu2+ and Zn2+ inhibited the incorporation of Fe2+ into protoporphyrin IX while Ni2 and Mg2+ had no effect on protoheme synthesis. Activity with Fe2+ and mesoporphyrin IX was less than with protoporphyrin IX but deuteroporphyrin IX produced the highest rate of protoheme synthesis. The membrane fraction containing ferrochelatase activity was found to insert Cu2+, Ni2+, Zn2+ and Co2+ enzymatically into protoporphyrin IX to produce metalloporphyrins. Cu2+ incorporation into protoporphyrin IX proceeded at a rate greater than with Fe2+ and theK
m for Cu2+ was 21.9 M. |
| |
Keywords: | Heme synthesis Iron metabolism Membranes Cation inhibition Metalloporphyrin |
本文献已被 SpringerLink 等数据库收录! |
|