Purification and subunit structure of extracellular superoxide dismutase from mouse lung tissue.
The first purification of mouse extracellular superoxide dismutase (EC-SOD) and the analysis of the native enzyme are described. Mouse EC-SOD was purified from lung tissues with a high recovery (41%) and a specific polyclonal antibody against the purified enzyme was obtained. The purified enzyme had a strong affinity for, heparin and a molecular mass of 150 kDa (estimated by a gel filtration chromatography). The native mouse EC-SOD was composed of two different sizes of subunits, a M(r) of 33 and 35 kDa (determined by SDS-PAGE). The 35-kDa subunit had an interchain disulfide bond at the C-terminus and existed as a covalent dimer in the molecule, whereas the 33-kDa subunit resulted from the 35-kDa subunit by truncating its C-terminus as a posttranslational modification, with resultant loss of the interchain disulfide bond. These results suggest that the native mouse EC-SOD is a heterotetramer composed of two different dimers, with or without a covalent bond.
Ookawara
T
T
Department of Hygiene, National Defense Medical College, Saitama, Japan.
Kizaki
T
T
Ohishi
S
S
Yamamoto
M
M
Matsubara
O
O
Ohno
H
H
D000818:Animals; D004220:Disulfides / Q000032:analysis; D005110:Extracellular Space / Q000201:enzymology; D015151:Immunoblotting; D008168:Lung / Q000201:enzymology*; D046911:Macromolecular Substances; D008297:Male; D051379:Mice; D008970:Molecular Weight; D013482:Superoxide Dismutase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism
D004220:Disulfides; D046911:Macromolecular Substances; D013482:Superoxide Dismutase