Demonstration using EPR spin-trapping of an oxygen-dependent, carbon-centered free radical generated by soybean lipoxygenase

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5020925

Carpenter, M F; Smith, F L

Purified prostaglandin synthase produces a carbon-centered, oxygen-dependent free radical which they have shown forms a spin-trapped adduct with 4-POBN and has characteristic hyperfine spin coupling constants (hfsc). As production of this radical is cyclooxygenase-dependent, additional studies on radical production were done using soybean lipoxygenase. The latter generates a lipid substrate-derived free radical trapped by the EPR spin trap 4-POBN (..cap alpha..-(4-pyridyl 1-oxide)N-tert-butyl nitrone). With linoleate as substrate, the hfsc are a/sub N/ = 15.5 G, a/sub ..beta..//sup H/ = 2.7 G. This signal is inhibited by ETYA, various antioxidants and heat inactivation of the enzyme. Additional hfsc are not seen when the enzyme is incubated in an /sup 17/O/sub 2/ atmosphere, but the signal is inhibited by anaerobeosis. Substitution of /sup 13/C 18 carbon free fatty acids from Chlorella pyrenoisdosa for linoleate produces 2 new lines for each of the original 6 observed with /sup 12/C substrate; the new spectrum has hfsc of a/sub N/ = 16.0 G, a/sub ..beta..//sup H/ = 2.4 G, a/sub ..beta..//sup 13/C = 4.2 G. This demonstrates that the radical is carbon centered and oxygen-dependent and appears not to be the same radical formed by enzymic hydrogen abstraction from the lipid substrate. This radical and the prostaglandin synthase-dependent radical appear to be nearly identical.

• Research Organization: Univ. of Oklahoma Health Science Center, Oklahoma City
• OSTI ID: 5020925
• 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

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
CARBON 12
CARBON 13
CARBON ISOTOPES
ELECTRON SPIN RESONANCE
ENZYME ACTIVITY
ENZYMES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FOOD
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEI
OXIDOREDUCTASES
OXYGEN 17
OXYGEN ISOTOPES
OXYGENASES
PLANTS
RADICALS
REACTION KINETICS
RESONANCE
SOYBEANS
STABLE ISOTOPES
TRACER TECHNIQUES
VEGETABLES