The Infrared Absorption Spectra of Unsaturated Fatty Acids and Esters<sup>1</sup>

Sinclair, Roger N.; McKay, A. F.; Myers, Gregory; Jones, Richard N.

doi:10.1021/ja01130a035

Cited by 143 publications

(76 citation statements)

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“…Its IR spectrum was like that of the 12,13-ketol from flax (29), containing absorptions characteristic of unsaturation (3,010 cm-'), a keto-carbonyl (1,720 cm-'), a hydroxyl (3,490 cm-'), and an ester carbonyl (1,740 cm-') (14). Absence of a trans double bond was indicated by the lack ofA at 970 cm-' (19 Product C was identified as 9-hydroxy-10-oxo-cis-12-octadecenoic acid (10,9-ketol The IR spectrum of product D was like that reported by Vick and Zimmerman (22), showing absorption bands characteristic of hydroxyl (3,610 cm-'), epoxy (900 cm-'), and ester carbonyl (1,740 cm-') groups (14). Absence ofA at 970 cm-' indicated the absence of a trans double bond (19).…”

Section: Methodsmentioning

confidence: 99%

“…Absence of a trans double bond was indicated by the lack ofA at 970 cm-' (19 Product C was identified as 9-hydroxy-10-oxo-cis-12-octadecenoic acid (10,9-ketol The IR spectrum of product D was like that reported by Vick and Zimmerman (22), showing absorption bands characteristic of hydroxyl (3,610 cm-'), epoxy (900 cm-'), and ester carbonyl (1,740 cm-') groups (14). Absence ofA at 970 cm-' indicated the absence of a trans double bond (19). A mass spectrum of the TMS derivative of the unsaturated methyl ester showed a molecular ion atm/e 398 and a peak at m/e 383 (M-15).…”

Section: Methodsmentioning

confidence: 99%

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Metabolism of Linoleic Acid by Barley Lipoxygenase and Hydroperoxide Isomerase

Lulai¹,

Baker²,

Zimmerman³

1981

Plant Physiol.

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The oxidation of linoleic acid in incubation mixtures containing extracts of barley lipoxygenase and hydroperoxide isomerase, and the production of these enzymes in quiescent and germinated barley, were investigated.The ratio of 9-hydroperoxylinoleic acid to 13-hydroperoxylinoleic acid was higher for incubation mixtures contain extracts of quiescent barley than for mixtures containing extracts of germinated barley, production of 13-hydroperoxylinoleic acid from germinated barley exceeded that of quiescent barley. Hydroperoxy metabolites of linoleic acid were converted to 9-hydroxy-1O-oxo-cis-12-octadecenoic acid, 13-hydroxy-10-oxo-tr-11-octadecenoic acid, and small amounts of 11-hydroxy-12,13-epoxy-cis-9-octadecenoic acid and 11-hydroxy-9,10-epoxy-cis-13-octadecenoic acid whether quiescent or germinated barley was the enzyme source; a fifth product, 13-hydroxy-12-oxo-cis-9-octadecenoic acid was formed only when germinated barley was the enzyme source.Lipoxygenase was readily extracted by buffer, but hydroperoxide isomerase was bound in a catalytically active state to the insoluble barley grist and was efficientiy extracted only when Triton X-100 was included in the extraction buffer. Hydroperoxide isomerase was locallzed in the embryo of quiescent barley, but it was present in the embryo, acrospire, and in small but concentrated amounts in the rootiet of germinating barley. The levels of both Lipoxygenase and hydroperoxide isomerase increased through the thirteenth day of germination.The importance of the LOX4 system to lipid metabolism in plant biochemistry and physiology is indicated by its near ubiquitous distribution in the plant kingdom (2)

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Metabolism of Linoleic Acid by Barley Lipoxygenase and Hydroperoxide Isomerase

Lulai¹,

Baker²,

Zimmerman³

1981

Plant Physiol.

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“…The absence of any indication of a trans double bond at 952 cm-' or 990 cm-' was most significant. Since the product of soybean lipoxidase is predominantly 13-hydroperoxyoctadeca-cis-9-trans-11-dienoic acid (5,11) (20), indicating that there was no reaction at the double bond in the 9, 10 position. The methyl ester of the keto compound was also examined by nuclear magnetic resonance spectroscopy and the results are shown in Figure 4.…”

mentioning

confidence: 99%

Hydroperoxide Isomerase

1970

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An enzyme has been isolated from flaxseed (Linum usitatissimum) which utilizes the product of lipoxidase for its substrate. The enzyme, termed hydroperoxide isomerase, converts the conjugated diene hydroperoxide of linoleic acid to the corresponding monoenoic ketohydroxy fatty acid. The structure of the latter has been determined by ultraviolet, infrared, and nuclear magnetic resonance spectroscopy; periodate and permangate oxidation; gas chromatography; and thin layer chromatography. Hydroperoxide isomerase activity has also been demonstrated in crude extracts from barley (Hordeum vulgare), wheat germ (Triticum aestivum), mung beans (Phaseolus aureus), and corn (Zea mays) and from partially purified extracts of soybean (Glycine max).The hydroperoxide isomerase enzyme from flaxseed has a pH optimum of 7.0. The enzyme was not inhibited by nordihydroguairetic acid, p-chloromercuribenzoic acid, or cyanide, but it was inhibited by cupric ion. One hundred per cent of the activity was lost by heating the enzyme for 1 minute at 68 C. Both

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“…The presence of a cis or trans double bond could be ascertained from the bending vibration at 965-975 cm 1 for trans configuration, as appears in elaidic acid (trans-9-octadecaenoic acid). Interestingly, this same study did reveal this band in arachidonic acid (24), suggesting it could have a trans double bond (Fig. 7).…”

Section: Geometry Of Double Bondsmentioning

confidence: 83%

“…IR spectroscopy was becoming available in chemical laboratories in the 1950s with the development of instrumentation that could measure the IR spectra of organic molecules. This technique was applied to the saturated and polyunsaturated fatty acids in order to assess the absorption characteristics of this class of molecules (24,25). The presence of a cis or trans double bond could be ascertained from the bending vibration at 965-975 cm 1 for trans configuration, as appears in elaidic acid (trans-9-octadecaenoic acid).…”

Section: Geometry Of Double Bondsmentioning

confidence: 99%