Double hydroperoxidation of alpha-linolenic acid by potato tuber lipoxygenase.
The potato tuber lipoxygenase preparations convert alpha-linolenic acid not only to 9(S)-HPOTE, but also to some more polar metabolites. Two of these polar products, I and II, with ultraviolet absorbance maxima at 267 nm were purified by HPLC. It was found that metabolites I and II have, respectively, one and two hydroperoxy groups. Products of NaBH4 reduction of both I and II were identified by their chemical ionization and electron impact mass spectra and by 1H-NMR spectra as 9,16-dihydroxy-10(E), 12(Z), 14(E)-octadecatrienoic acid. The obtained results suggest that compound II is 9.16-dihydroperoxy-10(E), 12(Z), 14(E)-octadecatrienoic acid and product I is a mixture of two positional isomers, 9-hydroxy-16-hydroperoxy-10(E),12(Z),14(E)-octadecatrienoic and 9-hydroperoxy-16-hydroxy-10(E),12(Z),14(E)-octadecatrienoic acids. Lipoxygenase converts efficiently [14C]9-HOTE into product I. Also, both metabolites I and II are the products of double dioxygenation. The second oxygenation at C-16 position as well as the first one at C-9 is controlled by lipoxygenase.
Grechkin
A N
AN
Institute of Biology, USSR Academy of Sciences, Kazan.
Kuramshin
R A
RA
Safonova
E Y
EY
Yefremov
Y J
YJ
Latypov
S K
SK
Ilyasov
A V
AV
Tarchevsky
I A
IA
D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D008042:Linolenic Acids / Q000378:metabolism*; D015227:Lipid Peroxidation; D008084:Lipoxygenase / Q000378:metabolism*; D013058:Mass Spectrometry; D011865:Radioisotope Dilution Technique; D011198:Solanum tuberosum / Q000201:enzymology*; D013056:Spectrophotometry, Ultraviolet
D002250:Carbon Radioisotopes; D008042:Linolenic Acids; D008084:Lipoxygenase