Files and links (1)
Published, Version of Record (VoR)Open Access (License Unspecified), Open
Journal article
Subcellular distribution of superoxide dismutases in human neutrophils. Influence of myeloperoxidase on the measurement of superoxide dismutase activity
Biochemical journal, v 166(2), pp 145-153
15 Aug 1977
PMID: 199157
Abstract
We have identified two distinct pools of superoxide dismutase in fractions of human peripheral neutrophils obtained by the isopycnic fractionation of homogenates of the latter with linear sucrose gradients. Superoxide dismutase activity, observed with polyacrylamide gels impregnated with Nitro Blue Tetrazolium, was present in: (1) the mitochondrial fraction [density (ρ) 1.169g/ml], containing the high-molecular-weight KCN-resistant enzyme, and (2) the cytoplasm fraction, containing the low-molecular-weight KCN-sensitive enzyme. Superoxide dismutase activity, observed with a quantitative assay involving cytochrome
c
, was present in: (1) the mitochondria, (2) the cytoplasm, and (3) the azurophil-granule fractions (ρ=1.206 and 1.222g/ml). No substantial enzyme activity was observed in specific-granule fractions (ρ=1.187g/ml) or in the membranous fraction (ρ=1.136g/ml) in either assay. The apparent superoxide dismutase activity observed in the azurophil granules with the cytochrome
c
assay was attributable not to true superoxide dismutase but to myeloperoxidase, an enzyme found solely in the azurophil granules. In the presence of H
2
O
2
, human neutrophil myeloperoxidase oxidized ferrocytochrome
c
. Thus, in the cytochrome
c
assay for superoxide dismutase, the oxidation of ferrocytochrome
c
by myeloperoxidase mimicked the inhibition of reduction of ferricytochrome
c
by superoxide dismutase. When myeloperoxidase was removed from azurophilgranule fractions by specific immuno-affinity chromatography, both myeloperoxidase and apparent superoxide dismutase activities were removed. It is concluded that there is no detectable superoxide dismutase in either the azurophil or specific granules of human neutrophils. Mitochondrial superoxide dismutase, 15% of the total dismutase activity of the cells, occurred only in fractions of density 1.160g/ml, where isocitrate dehydrogenase and cytochrome oxidase were also observed.
Metrics
Details
- Title
- Subcellular distribution of superoxide dismutases in human neutrophils. Influence of myeloperoxidase on the measurement of superoxide dismutase activity
- Creators
- Richard F. Rest - University of North Carolina at Chapel HillJohn K. Spitznagel - University of North Carolina at Chapel Hill
- Publication Details
- Biochemical journal, v 166(2), pp 145-153
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Microbiology and Immunology; [Retired Faculty]
- Web of Science ID
- WOS:A1977DS44200001
- Scopus ID
- 2-s2.0-0017643882
- Other Identifier
- 991020830854704721