La. Delrio et Rp. Donaldson, PRODUCTION OF SUPEROXIDE RADICALS IN GLYOXYSOMAL MEMBRANES FROM CASTOR BEAN ENDOSPERM, Journal of plant physiology, 146(3), 1995, pp. 283-287
The production of superoxide free radicals (O-2-radical-anion) by NADH
was investigated in glyoxysomal membranes from germinating castor bea
n (Ricinus communis L., cv. Hale) endosperm purified by treatment with
0.1 M Na2CO3. About 25 % of the NADH:cytochrome c reductase activity
in glyoxysomal membranes was mediated by O-2-radical-anion radicals in
duced by NADH. The rate of superoxide production by glyoxysomal membra
nes from castor bean endosperm (about 27 nmol O-2-radical-anion x mg(-
1) protein x min(-1)) was the highest measured so far in peroxisomal m
embranes. Incubation of membranes with an antibody against whole glyox
ysomal membrane proteins from castor bean endosperm produced an inhibi
tion of about 40 % in the NADH-dependent O-2-radical-anion generation,
whereas the O-2-radical-anion-independent NADH:cytochrome c reductase
activity was not affected. A superoxide dismutase isoenzyme was detec
ted by native gel electrophoresis and characterized as a Mn-superoxide
dismutase, and appeared to be a peripheral protein of glyoxysomal mem
branes. The NADH-induced generation of O-2-radical-anion radicals by g
lyoxysomal membranes from castor bean endosperm supports the idea that
the production of superoxide is a common metabolic property of peroxi
somal membranes. The possible function of Mn-superoxide dismutase in g
lyoxysomal membranes is discussed.