Lipoxygenase from potato tubers. Partial purification and properties of an enzyme that specifically oxygenates the 9-position of linoleic acid

Abstract

A lipoxygenase (EC 1.13.1.13) was partially purified from potato tubers and was shown to differ from previously characterized soya-bean lipoxygenases in the positional specificity and pH characteristics of the oxygenation reaction. The potato enzyme converted linoleic acid almost exclusively (95%) into 9-d-hydroperoxyoctadeca-trans-10,cis-12-dienoic acid. The 13-hydroperoxy isomer was only a minor product (5%). Linolenic acid was an equally effective substrate, which was also oxygenated specifically at the 9-position. The enzyme had a pH optimum at 5.5-6.0 and was inactive at pH9.0. A half-maximal velocity was obtained at a linoleic acid concentration of 0.1mm. No inhibition was observed with EDTA (1mm) and cyanide (1mm) or with p-chloromercuribenzoate (0.2mm). Haemoproteins were not involved in the lipoxygenase activity. The molecular weight of the enzyme was estimated from gel filtration to be approx. 10(5). Preliminary evidence suggested that the enzyme oxygenated the n-10 position of fatty acids containing a penta(n-3, n-6)diene structure.

The Reductase Activity of the Arabidopsis Caleosin RESPONSIVE TO DESSICATION20 Mediates Gibberellin-Dependent Flowering Time, Abscisic Acid Sensitivity, and Tolerance to Oxidative Stress

“…[1-14 C]13-HPOD and [1-14 C]13-HPOT were synthesized enzymatically from [1-14 C]linoleic acid (50 Ci mol 21 ) and [1-14 C]linolenic acid (50 Ci mol 21 ; PerkinElmer Life Sciences) in the presence of soybean (Glycine max) lipoxygenase (Sigma-Aldrich). Potato (Solanum tuberosum) lipoxygenase (Cayman Chemical, SPI-BIO) was used to obtain 9-HPOT from linolenic acid as described (Galliard and Phillips, 1971). [1-14 C]FAOOHs were incubated with purified RD20 (5 mg of protein) in 500 mL of 0.1 M sodium acetate (pH 5.5) for 2 h or overnight at 27°C.…”

Lipoxygenases Mediate the Effect of Essential Fatty Acid in Skin Barrier Formation

“…HPODE was prepared from linoleic acid using an extract of potato tuber (containing 9S-LOX) (25). Racemic 9-HPODE methyl ester was prepared by vitamin E-controlled autoxidation of methyl linoleate as described (26).…”

Caracterização bioquímica e cinética de lipoxigenases de plantas de soja submetidas à aplicação de ácidos graxos poliinsaturados

“…Os valores de pH ótimo observados estão dentro da faixa de pH ótimo verificada em lipoxigenases de várias plantas: batata, pH 5,5-6,0 (Galliard & Phillips, 1971); semente de girassol, pH 6,2 (Leoni et al, 1985); folhas de tomate, pH 6,4-7,2 (Koch et al, 1992); pepino, pH 5,0 (Avdiushiko et al, 1994); pimentão, pH 6,5 (Minguez-Mosqueira et al, 1993); semente de ervilha, pH 6,8 (Redgel et al, 1995), culturas de oliveira (Olea europaea), pH 5,5 e 6,0-6,5 (Williams et al, 2000) e folhas de soja do genótipo IAC-100 e IAC-100 TN, no estádio V3 de desenvolvimento, pH 4,5 e 6,0 (Vieira et al, 2001).…”