Spectrophotometric Determination of Vicinal Glycols

Dixon, Jonathan S.; Lipkin, David

doi:10.1021/ac60090a046

Cited by 418 publications

(77 citation statements)

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“…The enediol form of the molecule is very similar to the active center of ascorbic acid. The redox potential of the ketohydroxy fatty acid is different from that of ascorbic acid, however, since the ketohydroxy compound will reduce DCPIP at pH 7.4 but not at pH 4 (1)(2)(3)9). In each case, the description of the observed activity matches very closely that of the hydroperoxide isomerase observed in this study.…”

Section: Discussionsupporting

confidence: 75%

“…However, several properties of the enzyme are known. All of its activity was destroyed by heating for 1 min at 68 C or for 5.5 min at 55 C. All activity was lost when the assay was conducted in 4 Figure 6. The optimum for isomerase activity was pH 7.0, and lipoxidase showed two optima, one at pH 5.4 and another at pH 6 (Fig.…”

Section: Hqo H Ch1-(ch /)4--c-c--ch2--c=andc-(ch2)7--cooh H Ho Oh H H Cmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 75%

Section: Hqo H Ch1-(ch /)4--c-c--ch2--c=andc-(ch2)7--cooh H Ho Oh H H Cmentioning

confidence: 99%

Hydroperoxide Isomerase

1970

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“…The oxidation was completed 5 d later, and ethylene (0.5 ml) was added to the solution. Consumption of NaIO 4 was measured by a spectrophotometric method 16) and HCOOH production by titration with 0.01 M sodium hydroxide. The reaction mixture was reduced by NaBH 4 , neutralized by 0.1 M HOAc, dialyzed against distilled water, and the retentate was then lyophilized to give a product (PSGL-I-1A-O1, yield: 41 mg).…”

mentioning

confidence: 99%

Purification, Characterization, and Modification of T Lymphocyte-Stimulating Polysaccharide from Spores of <i>Ganoderma lucidum</i>

et al. 2002

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Ganoderma lucidum, a well-known Chinese medicinal fungus, has been used to promote health and longevity in East Asian countries. Its medical effects on cancer, hypertension, hepatitis, and hypercholesterolemia have been demonstrated by pharmacological studies in the past two decades. [1][2][3][4] This fungus has attracted considerable attention partly because the polysaccharides isolated from the fruit bodies and the mycelium have shown antitumor and hyperglycemic activity. 3,5,6) However, the active components in the spores of G. lucidum have rarely been studied owing to the difficulty in collection and sporoderm-breaking of the spores. Recently, with the successful cultivation of G. lucidum indoors on a large scale and a breakthrough in sporodermbreaking technology, much attention has been paid to chemical components of G. lucidum spores 7,8) and their versatile biological activities.9,10) More recently, we have reported an immunomodulating polysaccharide from the spores of G. lucidum. 11) In the present study, we deal with the purification and characterization of the T lymphocyte-stimulating polysaccharide, based on the activity-guided principle, from the hot-water extract of the sporoderm-broken spores of G. lucidum. A series of sulfated or carboxymethylated derivatives of the polysaccharide were successively prepared and their structures were elucidated by chemical and spectral methods. The solution conformation and T lymphocyte proliferation effect of the polysaccharide and its derivatives are compared and discussed. ExperimentalMaterials Spores of G. lucidum were collected in Shanxi Province, PR China. It was identified by Dr. Xiu-Lan Huang and stored as a voucher specimen (no. 99064) in the Herbarium of Phytochemistry Department of Shanghai Institute of Materia Medica, Shanghai, PR China. Before use, the sporoderm of the spores was ultrasonographically broken and the broken ratio was estimated about 60-80% by electronic microscopy. T-Dextran in a series of different molecular weights was obtained from Pharmacia. Concanavalin (Con A) was from Sigma and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was from Fluka. Medium RPMI-1640 was purchased from Gibco Laboratories. All other reagents were of the highest quality available and were used without further purification.Isolation and Purification of the T Lymphocyte-Stimulating Polysaccharide The sporoderm-broken spores of G. lucidum (1.0 kg), previously defatted with 95% alcohol, were decocted for 6 h with 10 l of water to half the original volume, and the residue was again decocted with 8 l of water. The combined aqueous extract was deproteinated with trichloroacetic acid, and the resulting aqueous fraction was extensively dialyzed against running water for 3 d and then against distilled water for 1 d (molecular weight cutoff 3000-5000 Da). The retentate was concentrated under reduced pressure to a small volume (1.8 l), and 4 volumes of ethanol were added stepwise with stirring at 4°C. Then the mixture was stored overnight at Ϫ10°C. T...

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“…Periodate consumption during the oxidation of sidechain polysaccharide was followed spectrophotometrically at 225 nm [8] on samples containing 0.05-0.25 pmol glucose equivalents in a total volume of 3.0 ml. For Smith degradation, sidechain oligosaccharide (5 mg; equivalent to 31.9 pmol glucose equivalents) was oxidised with 0.04 M sodium metaperiodate in 7 ml 0.1 M sodium acetate buffer, pH 4.9, in the dark at 4°C for 3 days.…”

Section: Periodate Oxidation and Smith Degradationmentioning

confidence: 99%