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Showing papers on "Phosphotungstic acid published in 1977"


Journal ArticleDOI
01 Nov 1977-Lipids
TL;DR: A normal chromatographic pattern can be restored by treating the precipitated gangliosides with the tetrasodium salt of ethylenediamine tetraacetic acid followed by dialysis, and TCA-PTA treatment does not appear to cause artifacts or hydrolysis of the gangLiosides.
Abstract: Trichloroacetic acid (TCA)-phosphotungstic acid (PTA) precipitation has been used as a faster procedure than dialysis for the isolation of gangliosides, but the TCA-PTA treatment causes striking abnormalities in the thin layer chromatographic mobilities of the gangliosides. However, a normal chromatographic pattern can be restored by treating the precipitated gangliosides with the tetrasodium salt of ethylenediamine tetraacetic acid followed by dialysis. Hence, TCA-PTA treatment does not appear to cause artifacts or hydrolysis of the gangliosides.

12 citations


Journal ArticleDOI
TL;DR: It was reported that following each treatment gangliosides, such as GDlb and GT1 which contain a chain of two sialyl groups are resolved by TLC into approximately equal amounts of two components, and internal esters are also formed by this TCA-PTA procedure.
Abstract: A NOTE recently published in this Journal (MESTRALLET et al., 1976) describes chromatographic changes that occur when purified single gangliosides are treated with trichloroacetic acid-phosphotungstic acid (TCA-PTA) precipitation reagent (DEVRIES & BARONDES 1971; MACCHIONI et al., 1974; PATT & GRIMES, 1974; DUNN, 1974). It was reported that following each treatment gangliosides, such as GDlb and GT1 which contain a chain of two sialyl groups are resolved by TLC into approximately equal amounts of two components. The slower moving component corresponds to the untreated ganglioside. Disialoganglioside (GDla), which has two sialyl groups not linked in a chain also formed a new chromatographic component but in lesser amounts. Monosialogangliosides were reported to be essentially not affected by the treatment. It is clearly important to understand these phenomena if the convenient precipitation procedures for purification of gangliosides are to be useful. Previous studies from our laboratory provide information that aid in the explanation of these phenomena. When hematoside (GM3) was isolated from bovine adrenal gland (MCCLUER & EVANS, 1972) by the conventional Folch method (FOLCH et al., 1957) a chromatographically altered product of GM3 was detected. During investigation of the structure of this ganglioside derivative, it was found that prolonged treatment with acetic acid converts most of the gangliosides to their internal esters. The internal esters are structures which involve the formation of an ester linkage between the sialic acid carboxyl group and a hydroxyl of the adjacent carbohydrate residue which is either another sialic acid residue or a galactose residue. The hydroxyls involved are either those on carbons 7 or 9 of sialic acid or those on carbons 2 or 4 of the galactose residue. Hematoside forms one such neutral ester, GDlb forms two detectable esters, one neutral and one still acidic, and GTl yields one neutral and two observable acidic substances. All of these derivatives can be reconverted to the original gangliosides by mild base hydrolysis. Since the TCA-PTA method involves acidic conditions we suspected that internal esters are also formed'by this procedure and decided to investigate this possibility.

11 citations


Journal ArticleDOI
TL;DR: A polychrome stain procedure was developed to demonstrate amastigotes of the protozoan parasite Leishmania braziliensis as well as cytoplasmic and other tissue components in cutaneous lesions of infected animals.
Abstract: A polychrome stain procedure was developed to demonstrate amastigotes of the protozoan parasite Leishmania braziliensis as well as cytoplasmic and other tissue components in cutaneous lesions of infected animals. The procedure is as follows: stain nuclei for 10 minutes with an iron hematoxylin containing 0.5% hematoxylin and 0.75% ferric ammonium sulfate dissolved in 1:1 0.6 N H2SO4:95% ethanol; rinse 4 minutes in distilled water. Cytoplasmic staining is achieved by exposing tissues for 10 minutes to a solution containing 0.25% Biebrich scarlet, 0.45% orange G, 0.5% phosphomolybdic acid and 0.5% phosphotungstic acid in 1% aqueous acetic acid. These first two solutions are modified from Whipf's polychrome stain. Sections are differentiated for 10 seconds in 50% ethanol, rinsed in water, stained 3 minutes in 0.1% aniline blue WS in saturated aqueous picric acid, rinsed in water and differentiated for 1 minute in absolute ethanol containing 0.05% acetic acid. Mordanting overnight in 6% picric acid in 95% eth...

3 citations