Purification and sequence of rat extracellular superoxide dismutase B secreted by C6 glioma.
An enzyme which converts radical oxygen, produced by phorbol 12-myristate 13-acetate activated neutrophils, into nonluminescent products is secreted by rat C6 glioma. The enzyme was purified from chemically defined conditioned media and identified as an extracellular superoxide dismutase (EC-SOD). The purified enzyme is distinct from human EC-SOD C (Hjalmarsson, K., Marklund, S. L., Engström, A., and Edlund, T. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 6340-6344) by its elution from heparin-Sepharose at 300-400 mM NaCl, its pI of 6.1-7.2, and its native M(r) of 85,000 +/- 20,000. The rat EC-SOD is a dimer with a subunit M(r) of 34,000-36,000 and is extensively modified by post-translational processing. Although rat EC-SOD has a high sequence homology with the catalytic center and the polybasic heparin-binding site near the COOH terminus of human EC-SOD C, its NH2-terminal sequence and the sequences flanking the heparin-binding site differ substantially. The sequence of the isolated rat EC-SOD cDNA fully confirms the data obtained from amino acid sequence analysis. The amino acid sequence of the enzyme and its biochemical properties support its identification as the rat EC-SOD B.
Willems
J
J
Interdisciplinary Research Center, KULAK, Kortrijk, Belgium.
Zwijsen
A
A
Slegers
H
H
Nicolaï
S
S
Bettadapura
J
J
Raymackers
J
J
Scarcez
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D017077:Culture Media, Conditioned; D018076:DNA, Complementary; D005910:Glioma / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000235:genetics / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D017077:Culture Media, Conditioned; D018076:DNA, Complementary; D007527:Isoenzymes; D013482:Superoxide Dismutase