Differential Expression of Lipoxygenase Isoenzymes in Embryos of Germinating Barley

Holtman, W.; Duijn, G. Van; Sedee, N. J. A.; Douma, A.C.

doi:10.1104/pp.111.2.569

Cited by 44 publications

(36 citation statements)

References 11 publications

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“…3) may be due to only one possible orientation mode as a result of the esterification. This is in-line with observations reported by Holtman et al for barley LOX (20,21). The incubation of linoleic acid with extracts from germinating barley embryos was found to give rise to the production of 9-HPOD as the main product; however, when acting on esterified lipids the main LOX product was 13-HPOD.…”

Section: Discussionsupporting

confidence: 92%

Oxidation of Dilinoleoyl Phosphatidylcholine by Lipoxygenase 1 from Soybeans

Pérez‐Gilabert

Veldink

Vliegenthart

1998

Archives of Biochemistry and Biophysics

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Soybean lipoxygenase-1 is able to oxidize dilinoleoyl phosphatidylcholine at pH 7.5 and 10. The reaction could be followed spectrophotometrically from the increase of the absorbance at 234 nm. An intermediate product and a final product were detected. In the intermediate product only one of the linoleoyl chains (either sn1 or sn2) was oxidized. In the final product, both linoleic acid units were converted into hydroperoxides. Apparently, oxidation of one of the linoleoyl chains leads to a disruption of the structure of the mixed bilayer disk, making the remaining fatty acid unit more accessible to the action of the enzyme. The specificity of lipoxygenase-1 when acting on phospholipids is not affected by pH. The exclusive production of 13-hydroperoxyoctadecadienoic acid derivatives of dilinoleoyl phosphatidylcholine at pH 7.5 and 10 may result from the blockage of the carboxylic end of the fatty acid.

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Section: Discussionsupporting

confidence: 92%

Oxidation of Dilinoleoyl Phosphatidylcholine by Lipoxygenase 1 from Soybeans

Pérez‐Gilabert

Veldink

Vliegenthart

1998

Archives of Biochemistry and Biophysics

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“…To test separation of the LOX isoenzymes at the protein level, western blotting experiments were performed, as described by Holtman et al [17]. These experiments showed that fraction 23 only contained LOX-2, while fraction 15 only contained LOX-I (data not shown).…”

Section: Resultsmentioning

confidence: 99%

Lipoxygenase‐2 Oxygenates Storage Lipids in Embryos of Germinating Barley

Holtman¹,

Vredenbregt-Heistek²,

Schmitt

et al. 1997

European Journal of Biochemistry

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differ in temporal expression, suggests different physiological functions for the two isoenzymes at the onset of germination. We aimed to obtain more information about these functions by studying the substrate and product specificities of both isoenzymes. Analyses of the products formed from linoleic acid confirmed that LOX-I oxygenated at C9, and LOX-2 at C13. When testing more complex substrates, it was found that both LOX-1 and LOX-2 were capable of metabolizing esterified fatty acids. K,,, values from both isoenzymes for free fatty acids were much lower than for esterified fatty acids (7-35-fold for LOX-I versus 2-Wold for LOX-2). Interestingly, LOX-I showed significantly higher K,,, values for esterified fatty acids than did LOX-2. This was reflected by analyses of the products formed from di-and tri-linoleoylglycerol ; LOX-2 formed higher amounts of oxygenated polyunsaturated fatty acids within the esterified lipids than did LOX-I, with a corresponding larger extent of oxygenation.In order to identify potential endogenous substrates, we analyzed free and esterified lipids in total lipid extracts from barley after different periods of germination for LOX-derived products. The results indicated that esterified fatty acids were preferentially metabolized by LOX-2 activity. Analysis of the positional specificity within the lipids after alkaline hydrolysis revealed that only (1 3s)-hydroxy derivatives were formed, indicating the in vivo action of LOX-2. These data show that LOX-2 is capable of oxygenating storage lipids and suggest that during the onset of germination LOX-2 may be involved in oxygenation of esterified polyunsaturated fatty acids in barley seeds. We suggest that the oxygenation of these lipids precedes the onset of their catabolism and that the degradation product, (9Z,IlE,13S)-13-hydroxy-octadecadienoic acid, serves as an endogenous substrate for Boxidation and therefore as a carbon source for the growing barley embryo.

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“…LOX-1 is present in both quiescent and germinating barley grains and accounts for most of the LOX activity in mature barley grains. LOX-2 is detected only at early stages of grain development and after germination (Holtman et al, 1996;Schmitt and van Mechelen, 1997;van Mechelen et al, 1999). The LOX-1 isoform is encoded by the LoxA gene (GenBank L35931) located in chromosome arm 4HS, whereas the LOX-2 isoform is encoded by the LoxC gene (GenBank L37358) mapped on chromosome arm 5HL (van Mechelen et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

A deletion at the Lpx-B1 locus is associated with low lipoxygenase activity and improved pasta color in durum wheat (Triticum turgidum ssp. durum)

Carrera

Echenique

Zhang

et al. 2007

Journal of Cereal Science

115

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The concentration of yellow carotenoid pigments in durum wheat grain is an important quality criterion and is determined both by their accumulation and by their degradation by lipoxygenase enzymes (Lpx loci). The existence of a duplication at the Lpx-B1 locus and the allelic variation for a deletion of the Lpx-B1.1 copy is reported. This deletion was associated with a 4.5-fold reduction in lipoxygenase activity and improved pasta color (Po0.0001) but not semolina color, suggesting reduced pigment degradation during pasta processing. A molecular marker for the deletion was mapped on chromosome 4B in a population obtained from the cross between durum line UC1113 and variety Kofa. A second lipoxygenase locus, designated Lpx-A3, was mapped on the homoeologous region on chromosome 4A and was associated with semolina and pasta color (Po0.01) but not with lipoxygenase activity in the mature grain. Selection for both the UC1113 allele for Lpx-A3 and the Kofa Lpx-B1.1 deletion resulted in a 10% increase in yellow scores for dry pasta relative to the opposite allele combination. This result indicates that the markers and the new allelic variants reported here will be useful tools to manipulate the wheat Lpx loci and to improve pasta color. r

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Differential Expression of Lipoxygenase Isoenzymes in Embryos of Germinating Barley

Cited by 44 publications

References 11 publications

Oxidation of Dilinoleoyl Phosphatidylcholine by Lipoxygenase 1 from Soybeans

Oxidation of Dilinoleoyl Phosphatidylcholine by Lipoxygenase 1 from Soybeans

Lipoxygenase‐2 Oxygenates Storage Lipids in Embryos of Germinating Barley

A deletion at the Lpx-B1 locus is associated with low lipoxygenase activity and improved pasta color in durum wheat (Triticum turgidum ssp. durum)

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