Azide protection of bacteroides superoxide dismutases from inactivation by hydrogen peroxide
Conference
·
· Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:5243947
The anaerobes Bacteroides fragilis, B. distasonis and B. thetaiotaomicron produce an iron-containing superoxide dismutase (FeSOD). These FeSODs are reversibly inhibited by 1 mM azide (NaN/sub 3/) and are irreversibly inactivated upon incubation with hydrogen peroxide (H/sub 2/O/sub 2/). H/sub 2/O/sub 2/ inactivation of the enzyme likely depends on a Fenton type reaction with the production of hydroxyl radical (OH). Addition of NaN/sub 3/ to the enzyme solution decreased the rate of inactivation by H/sub 2/O/sub 2/. After 20 minutes incubation of purified B. distasonis FeSOD with 2.5 mM H/sub 2/O/sub 2/, 61% of the initial enzymatic activity remained when 1 mM NaN/sub 3/ was also present compared with 29% activity without NaN/sub 3/. Similar results were seen with FeSOD from B. fragilis and B. thetaiotaomicron. Metal analyses of the native, peroxidized, and NaN/sub 3/ protected samples are consistent with loss of Fe from the enzyme upon peroxidation, but retention of Fe and enzymatic activity in the NaN/sub 3/ protected sample. Protection of FeSOD activity from H/sub 2/O/sub 2/ inactivation was dependent on NaN/sub 3/ concentration. Anionic hydroxyl radical scavengers, such as urate and xanthine did not significantly protect the enzyme. The results are consistent with binding of azide to the active site either preventing entry of H/sub 2/O/sub 2/ or altering Fe redox potential, preventing OH production.
- Research Organization:
- Virginia Tech, Blacksburg
- OSTI ID:
- 5243947
- Report Number(s):
- CONF-8606151-
- Conference Information:
- Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
560121* -- Radiation Effects on Cells-- External Source-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANIMALS
AQUEOUS SOLUTIONS
CATALASE
CELL CONSTITUENTS
CYTOPLASM
DISPERSIONS
ELEMENTS
ENZYME ACTIVITY
ENZYMES
IONIZING RADIATIONS
IRRADIATION
LETHAL IRRADIATION
MAMMALS
MICE
MIXTURES
NONMETALS
OXIDOREDUCTASES
OXYGEN
PEROXIDASES
RADIATIONS
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
RODENTS
SOLUTIONS
SUPEROXIDE DISMUTASE
TUMOR CELLS
VERTEBRATES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANIMALS
AQUEOUS SOLUTIONS
CATALASE
CELL CONSTITUENTS
CYTOPLASM
DISPERSIONS
ELEMENTS
ENZYME ACTIVITY
ENZYMES
IONIZING RADIATIONS
IRRADIATION
LETHAL IRRADIATION
MAMMALS
MICE
MIXTURES
NONMETALS
OXIDOREDUCTASES
OXYGEN
PEROXIDASES
RADIATIONS
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
RODENTS
SOLUTIONS
SUPEROXIDE DISMUTASE
TUMOR CELLS
VERTEBRATES