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1.
Neutral glycosphingolipids were isolated from the colon of rats between birth and adulthood. The glycolipid concentration was stable during this period. Epithelial cells of the adult colon contained three times more glycolipids than the whole organ. The distribution pattern underwent only minor modifications during development. Free ceramide contributed for 23-27% of the total neutral sphingolipids at all ages. In 6-day-old rats, it was constituted of nonhydroxylated fatty acids linked to C18-sphingenine (57.3% of the bases), C18- and C20-4D-hydroxysphinganine (24.2 and 14.0% of the bases, respectively). This composition was essentially maintained during development. Glucosylceramide was the major glycolipid at all ages (40-50% of the total neutral sphingolipid content). At birth, 40% of its fatty acids were 2-hydroxylated and 93% of the bases were C18-4D-hydroxysphinganine. In adult epithelial cells, 75% of the fatty acids were 2-hydroxylated and C18- and C20-4D-hydroxysphinganine contributed for 66 and 25% of the bases, respectively. A transient increase of the contribution of nonhydroxylated fatty acids and C18-sphingenine was observed during the first week of life. C20-4D-hydroxysphinganine, which was characterized by gas-liquid chromatography of its aldehydes after periodate oxidation and of its N-acetyl O-trimethylsilyl derivatives, appeared after birth and reached 20% of the bases after two weeks. These findings are another example of the specificity of the lipidic part of glucosylceramide during the ontogenic differentiation.  相似文献   

2.
Neutral glycolipids were purified from the glandular part of the stomach of rats of different ages from 20 days of gestation to 60 days after birth. The two major glycolipids were identified as glucosylceramide and isogloboside. Free ceramide was also detected. The concentrations of these sphingolipids remained almost stable with development. Monohexosylceramide contained 55 and 68% of 2-hydroxylated fatty acids at 20 and 22 days of gestation, respectively, and 82% in the adult. Its three major bases, C18-sphingenine, C18- and C20-4D-hydroxysphinganine were characterized by gas-liquid chromatography and mass spectrometry of their N-acetyl-O-trimethylsilyl derivatives. The occurrence of the bases changed with development. C18-sphingenine contributed for 26% of the bases at birth and 65% in the adult. Conversely, C18-4D-hydroxysphinganine contributed for 35% of the bases at birth and 9% in the adult. The ceramide part of isogloboside consisted of nonhydroxylated fatty acids and mainly C18-sphingenine throughout development. The percentage of long-chain fatty acids was higher in older animals. These results stressed the specificity of the lipidic part of the rat gastric glycolipids and their specific evolution during the development.  相似文献   

3.
Spiroplasma strains from plant and arthropod hosts, and from surfaces of flowers, were classified into three serological groups (designated I, II, and III) based on results from growth-inhibition tests. No significant cross reactions were observed among groups. The groupings were confirmed by ring-interface precipitin and microprecipitin tests, using membrane preparations as test antigens, and by organism-deformation tests. Serogroup I contained three subgroups: subgroup A (Spiroplasma citri strains Maroc R8A2 and C189), subgroup B (strain AS 576 and closely related strains from honeybee or flowers), and subgroup C (corn stunt spiroplasma strains). Serogroup II contained strains 23-6 and 27-31 isolated from flowers of the tulip tree (Liriodendron tulipifera L.) growing in Maryland. Serogroup III contained strains SR 3 and SR 9 isolated from flowers of the tulip growing in Connecticut. The subgroups of serogroup I were based on organism deformation, microprecipitin, and ring-interface precipitin tests. The data are consistent with the hypothesis that the three serogroups represent no less than three distinct spiroplasma species.  相似文献   

4.
1. Phosphoprotein phosphatase (phosphoprotein phosphohydrolase EC 3.1.3.16) in the soluble fraction of rabbit liver which catalyzes the dephosphorylation of muscle phosphorylase a and phosphohistone (P-histone) was resolved into three active fractions by NaCl gradient elution from a DEAE-cellulose column (Fraction I, 11 and III in order of elution). They have different relative reaction rates for the two substrates and different degrees of stimulation by Mn-2+. Apparent Km values of Fraction I, II and III were 15, 20 and 16 muM for phosphorylase a, and 6.9, 5.3 and 4.4 muM for P-histone, respectively (with Mn-2+ in the assay mixture). 2. On sucrose density gradient centrifugation Fraction I and II were revealed to contain a major peak (7.0 S and 7.8 S, respectively) and a minor peak (4.0 S) of activity, while Fraction III contained only one peak (5.8 S). Freezing and thawing in the presence of 0.2 M mercaptoethanol dissociated all three fractions into subunits of similar molecular size (3.4 S), with concomitant enhancement of phosphorylase phosphatase activity. The Km values all became essentially the same (20 muM for phosphorylase a and 16 muM for P-histone). 3. The phosphorylase phosphatase and P-histone phosphatase activities could not be separated with any of the procedures described. Competition between the two phosphoprotein substrates was observed with some of the fractions.?  相似文献   

5.
Synopsis The coloured components in the high-iron diamine dye bath were separated into three fractions using column chromatography on Sephadex G-10. These fractions were called Fraction I, II and III in order of their emergence from the column. From atomic absorption measurements, part of Fraction I was found to be free of iron. Most of Fraction II and the whole of Fraction III contained only trace amounts of iron. Therefore, the three Fractions were investigated further. All experiments were carried out at pH 1.4 (corresponding to the pH of the original high-iron diamine bath).Fraction I was violet, Fraction II red-violet and Fraction III aniline-red; the extinction maxima in the visible region were 560, 526 and 540 nm respectively. On electrophoresis, the Fractions were not quite homogeneous, although most of Fractions I and II migrated in the same front and much faster than Fraction III. The high-iron diamine solution separated into two main fractions, one of which corresponded in colour and velocity to Fractions I and II and the other to Fraction III.In histochemical experiments, Fractions I, II and III bound to tissue sites containing sulphated mucosaccharides or nucleic acids; from histochemical enzyme digestion tests or by using purified materials in spot tests on cellulose acetate membrane, it was confirmed that the diamines were bound to RNA and DNA. However, when ferric chloride was added to any of the Fractions in an amount corresponding to that in the original high-iron diamine dye bath, the binding to tissue sites containing nucleic acids was inhibited but the reaction with sulphated mucosubstances was not affected. Also, in the presence of added ferric chloride, the anomalous binding of Fraction I to carboxyl groups of mouse sublingual gland sialomucin was prevented.It is concluded that ferric chloride in the high-iron diamine dye bath prevents diamine complexes from binding with nucleic acids, and apparently with carboxymucins too. Further, this conclusion substantiates our previous observations of the central role ferric chloride plays in making the histochemical high-iron diamine technique specific for sulphated mucosubstances.  相似文献   

6.
Fractionation of sorbitol metabolites in the culture liquid of Gluconobacter melanogenus IFO 3292 was examined by column chromatographic techniques. Ion exchange column chromatography of the culture supernatant allowed to divide the components of the metabolites into Fractions I, II, III and IV. Paperelectrophoretic and paperchromatographic analyses of these fractions revealed that Fractions I, II, III and IV contained neutral sugar, hexonic acids, 5-ketohexonic acid and 2-ketohexonic acids, respectively.

The neutral sugar in Fraction I, the 5-ketohexonic acid in Fraction III and the 2-ketohexonic acids in Fraction IV were isolated and determined to be l-sorbose, 5-keto-d- mannonic, 2-keto-d-gluconic and 2-keto-l-gulonic acids, respectively, from their physical properties. In Fraction II were contained two different hexonic acids, one of which was identified to be l-idonic acid by the aid of substrate specificity of a hexonic acid dehydrogenase of Pseudomonas aeruginosa, and the other was determined to be d-mannonic acid as the phenylhydrazide derivative.  相似文献   

7.
Free ceramide, glucosylceramide, and sphingomyelin were isolated from mature cells of adult rat small intestine. Free ceramide and ceramide cleaved from sphingomyelin by enzymatic hydrolysis were fractionated by thin-layer chromatography on borate-impregnated silica gel plates. Sphingoid bases were characterized by gas-liquid chromatography of aldehydes formed upon periodate oxidation. Fatty acids were quantified as methyl esters. Ceramide structures were confirmed by direct-inlet mass spectrometry. Free ceramide was found to contain two major long-chain bases in nearly equal quantity: sphingosine, mainly linked to palmitic acid, and 4D-hydroxysphinganine associated with C20 to C24 fatty acids, 22% being hydroxylated. Sphinganine occurred as a minor component linked to nonhydroxy fatty acids. Sphingomyelin contained the three long-chain bases and 63% of its ceramide was N-palmitoyl-sphingosine. Mass spectrometry of glucosylceramide confirmed 4D-hydroxyshingamine as the major sphingoid base associated preferentially with longer chain hydroxy fatty acids.  相似文献   

8.
While invertebrates store neutral lipids as their major energy source, little is known about triacylglycerol (TAG) class composition and their differential catabolism in aquatic arthropods. This study focuses on the composition of the main energy source and its catabolism by lipase from the midgut gland (hepatopancreas) of the crustacean Macrobrachium borellii. Silver-ion thin-layer chromatography of prawn large TAG deposit (80% of total lipids) and its subsequent fatty acid analysis by gas chromatography allowed the identification of 4 major fractions. These are composed of fatty acids of decreasing unsaturation and carbon chain length, the predominant being 18:1n-9. Fraction I, the most unsaturated one, contained mainly 20:5n-3; fraction II 18:2n-6; fraction III 18:1n-9 while the most saturated fraction contained mostly 16:0. Hepatopancreas main lipase (Mr 72 kDa) cross-reacted with polyclonal antibodies against insect lipase, was not dependent on the presence of Ca2+ and had an optimum activity at 40 °C and pH 8.0. Kinetic analysis showed a Michaelis–Menten behavior. A substrate competition assay evidenced lipase specificity following the order: 18:1n-9-TAG > PUFA-enriched-TAG > 16:0-TAG different from that in vertebrates. These data indicate there is a reasonable correspondence between the fatty acid composition of TAG and the substrate specificity of lipase, which may be an important factor in determining which fatty acids are mobilized during lipolysis for oxidation in crustaceans.  相似文献   

9.
Studies on the assembly of apo B-100-containing lipoproteins in HepG2 cells   总被引:10,自引:0,他引:10  
The relationship between apoB-100 and the membrane of the endoplasmic reticulum (ER) has been studied by a combination of pulse-chase methodology and subcellular fractionation. HepG2 cells were pulse-labeled with [35S]methionine for 3 min and chased with cold methionine for periods between 0 and 20 min. ApoB-100 and albumin, present in the membrane as well as in the luminal content of the ER vesicles, were isolated after each chase period. The results indicated that apoB-100 was cotranslationally bound to the membrane of the ER, and from this membrane-bound form, was transferred to the lumen after a delay of 10-15 min. Albumin was, as could be expected for a typical secretory protein, cotranslationally sequestered in the lumen of the ER. Apo-B-100-containing lipoproteins present in the microsomal lumen were analyzed by ultracentrifugation in a sucrose gradient. ApoB-100 occurred on rounded particles in three density regions: (i) d 1.1065-1.170 g/ml (Fraction I), (ii) d 1.011-1.045 g/ml (Fraction II), and (iii) d less than 1.011 g/ml (Fraction III). Fraction I, isolated from cells cultured in the absence of oleic acid, contained a homogenous population of particles with a mean diameter of approximately 200 A. Fraction I isolated from cells cultured in the presence of oleic acid was slightly more heterogeneous and had a mean diameter of approximately 250 A. Fractions II and III had mean diameters of 300 and 500 A, respectively. Cholesterol esters and triacylglycerol were the quantitatively dominating lipid constituents of all three fractions. Pulse-chase experiments indicated that Fraction I contained the newly assembled lipoproteins. With increasing chase time, the apoB-100 radioactivity was redistributed from Fraction I to Fractions II and III, indicating that Fraction I is converted into Fractions II and III during the intracellular transfer. Particles corresponding to Fractions II and III were by far the most abundant lipoproteins found in the medium. The results presented support the possibility of a sequential assembly of apoB-100-containing lipoproteins.  相似文献   

10.
Proteoglycans were extracted with 4 M guanidine–HCl from the zone of maturing chondrocytes, the site of endochondral ossification of growing antlers of wapiti (Cervus elaphus). Proteoglycans were isolated by DEAE-Sephacel chromatography and separated by Sepharose CL-4B chromatography into three fractions. Fraction I contained a high molecular mass (>1000 kDa) chondroitin sulfate proteoglycan capable of interacting with hyaluronic acid. Its amino acid composition resembled that of the cartilage proteoglycan, aggrecan. Fraction II contained proteoglycans with intermediate molecular weight which were recognized by monoclonal antibodies specific to chondroitin sulfate and keratan sulfate. Fraction III contained a low molecular mass (<160 kDa) proteoglycan, decorin, with a glucuronate-rich glycosaminoglycan chain.  相似文献   

11.
三个新2,2—二甲基苯并二氢吡喃类化合物的分离与鉴定   总被引:5,自引:0,他引:5  
从中药三叉苦(Evodia lepta(Spreng.)Merr.)的地上部分分离鉴定了4个化合物。通过光谱解析和结构沟通的方法确定了它们的结构。其中3个为新化合物,依次命名为leptin A(Ⅰ)、leptin B(Ⅱ)和leptin C(Ⅲ)。另外一个已知化合物为异吴茱萸酮酚(Ⅳ)。  相似文献   

12.
Lipids were extracted from bovine brain myelin using a mixture of hexane and isopropanol (32). Myelin lipids were resolved, using Sep Pak chromatography, into four fractions: Fraction 1 contained neutral lipids, fraction 2, free fatty acids, fraction 3, ethanolamine phospholipids and fraction 4, choline phospholipids. Docosahexanoic (DHA) and arachidonic (AA) acids in these fractions were measured by RPHPLC. Fraction 2 was analyzed directly, the other three fractions were subjected to alkaline hydrolysis before analysis for DHA and AA. DHA and AA were not found in fraction 1. Both DHA and AA were found in fractions 2 and 3. Only AA was consistently found in fraction 4. These results were confirmed by GC.  相似文献   

13.
Acid hydrolyzates of waxy-maize starch were separated to give Fractions I, II, and III [T. Watanabe, and D. French, Carbohydr. Res., 84 (1980) 115-123]. Watanabe and French suggested that Fraction II, which contains approximately 25 D-glucose residues including an alpha-D-(1----6)-linked branch, has a double helical structure. In the present study, the thermodynamics of binding of iodine to Fractions II and III, and debranched Fraction II (Fraction II') was measured by isothermal-flow calorimetry. If four binding sites for Fraction II and two for Fractions II' and III are assumed, the standard free-energy changes, delta Gb0, for the binding of I2 are -18.5, -18.8, and -18.4 kJ X (mol I2)-1, and the enthalpy changes, delta Hb, are -28.4, -24.7, and -26.9 kJ X (mol I2)-1, respectively. The similarity of these values for the three fractions indicates that the conformation of Fraction II is essentially the same as those of Fractions II' and III, and that Fraction II, therefore, does not have a double helical structure in solution. The values for delta Gb0 are approximately 15 kJ X mol-1 less negative, and those for delta Hb approximately 40 kJ X mol-1 less negative than published values for the starch-I2 complex. These differences are due to the relatively very short D-glucose chains in the amylodextrin fractions employed in the present work.  相似文献   

14.
Enzymatic heme oxygenase activity has been partially purified from extracts of the unicellular red alga Cyanidium caldarium, and the macromolecular components have been separated into three protein fractions, referred to as Fractions I, II, and III, by serial column chromatography through DEAE-cellulose and Reactive Blue 2-Sepharose. Fraction I is retained by DEAE-cellulose at low salt concentration and eluted by 1 M NaCl. Fraction II is retained by Blue Sepharose at low salt concentration and eluted by 1 M NaCl. Fraction III is retained on 2',5'-ADP-agarose and eluted by 1 mM NADPH, while Fraction II is not retained on ADP-agarose. Fractions I-III, have Mr values of 22,000, 38,000, and 37,000, respectively (all +/- 2,000), as determined by Sephadex gel filtration chromatography. In vitro heme oxygenase activity requires the presence of all three fractions, plus substrate, O2, reduced pyridine nucleotide, and another reductant. Ascorbate, isoascorbate, and phenylenediamine serve equally well as the second reductant, but hydroquinone can also be used, with lower activity resulting. Fractions I-III are heat sensitive and inactive by Pronase digestion. Fraction I has a visible absorption spectrum similar to that of ferredoxin and is bleached by dithionite reduction or incubation with p-hydroxymercuribenzoate. Fraction I can be replaced by commercially available ferredoxin derived from the red alga Porphyra umbilicalis, and to a smaller extent, by spinach ferredoxin. Fraction III contains ferredoxin-linked cytochrome c reductase activity and can be partially replaced by spinach ferredoxin-NADP+ oxidoreductase. Reconstituted heme oxygenase and ferredoxin-linked cytochrome c reductase activities are both abolished if Fraction I or III is preincubated with 0.1 mM p-hydroxymercuribenzoate, but heme oxygenase activity is only slightly affected if Fraction II is preincubated with p-hydroxymercuribenzoate. Preincubation of Fraction II with 0.5 mM diethylpyrocarbonate inactivates heme oxygenase in the reconstituted system, and 10 microM mesohemin partially protects this Fraction against diethylpyrocarbonate inactivation. Algal heme oxygenase is inhibited 80% by 2 microM Sn-protoporphyrin even in the presence of 20 microM mesohemin. Fraction II is rate limiting in unfractionated and reconstituted incubation mixtures. None of the three cell fractions could be replaced by bovine spleen microsomal heme oxygenase or NADPH-cytochrome P450 reductase.  相似文献   

15.
This study was conducted to identify the sourness-suppressing peptides in cooked pork and to clarify the mechanism of sour taste suppression by the peptides. An extract prepared from pork loins vacuum-cooked at 60 degrees C for 6 hours after conditioning at 4 degrees C for 20 days was separated into three fractions: under MW 500 (Fraction I), MW 500-1,000 (Fraction II), and over MW 1,000 (Fraction III). The Fraction I content was largest. As judged by sensory evaluation, the addition of Fraction II was capable of suppressing stronger sourness than the other fractions. Fraction II also enhanced umami and saltiness. Three peptides (APPPPAEVHEVV, APPPPAEVHEVVE, and APPPPAEVHEVHEEVH) in Fraction II increased greatly during conditioning. A common peptide, APPPPAEVHEV, in the amino acid sequences of the three peptides suppressed the sour taste. The mechanism of sourness suppression by the peptide was concluded to comprise inhibition of the binding of sour taste substances to the membranes of the tongue.  相似文献   

16.
This study was conducted to identify the sourness-suppressing peptides in cooked pork and to clarify the mechanism of sour taste suppression by the peptides. An extract prepared from pork loins vacuum-cooked at 60 °C for 6 hours after conditioning at 4 °C for 20 days was separated into three fractions: under MW 500 (Fraction I), MW 500–1,000 (Fraction II), and over MW 1,000 (Fraction III). The Fraction I content was largest. As judged by sensory evaluation, the addition of Fraction II was capable of suppressing stronger sourness than the other fractions. Fraction II also enhanced umami and saltiness. Three peptides (APPPPAEVHEVV, APPPPAEVHEVVE, and APPPPAEVHEVHEEVH) in Fraction II increased greatly during conditioning. A common peptide, APPPPAEVHEV, in the amino acid sequences of the three peptides suppressed the sour taste. The mechanism of sourness suppression by the peptide was concluded to comprise inhibition of the binding of sour taste substances to the membranes of the tongue.  相似文献   

17.
A fractionation of Chromatium vinosum into an outer layer (cell wall) and three intracellular membrane fractions by isopycnic sucrose density centrifugation of a total membrane fraction obtained by lysis of lysozyme-EDTA spheroplasts is decribed. The three intracellular fractions (I, II, and III) have apparent densities of 1.11, 1.14, and 1.16, respectively, and contain the bulk of the photosynthetic pigments. Fraction II is enriched in bacteriochlorophyll and contains about 49% of the total membrane protein and 60% of the membrane bacteriochlorophyll. The outer membrane fraction (IV, cell wall) has a density of 1.23 and contains 5% of the membrane protein and 0.8% of the bacteriochlorophyll. Fraction I is enriched in lipids and phosphorus and has only a trace of diaminopimelate (DAP). Fractions II and III both contain a significant content of DAP. Fraction IV has no DAP, but has a fatty acid composition similar to that of the envelope fraction. Electrophoresis of the fractions on sodium dodecylsulfate-containing gels yielded from 8–13 bands of protein. Fractions I, II, and III contained the same series of unique proteins, while fraction IV contained another group of unique proteins. In fraction IV the bulk of the proteins traveled in one band with a molecular weight of 41,500. Examination of the fractions and whole spheroplasts in the electron microscope showed that fractions I, II and III were composed of large membrane structures in the form of membrane reticulum with bud-like appendages, and elongated flattened tubes. Fraction IV was composed of large ovoid structures which were seen to lie on the outer surface of the whole spheroplasts. These results suggest that the normal in vivo state of the intracellular membranes is that of an interconnected series of tubules and vesicles extending throughout the cell cytoplasm.  相似文献   

18.
The effects of male-derived extracts on female receptivity were investigated in Callosobruchus maculatus (Coleoptera: Bruchidae). Injection of aqueous extracts of the male reproductive tract into the abdomen of females reduced receptivity. Aqueous extracts of male reproductive tracts were divided to three molecular weight (MW) fractions by ultrafiltration: Fractions: (I) MW<3 kDa, (II) 3-14 kDa, and (III)>14 kDa. Fraction II reduced female receptivity from 3h after injection, and Fraction III reduced female receptivity from 2 days after injection. On the other hand, no effect on receptivity was found for Fraction I. Furthermore, male reproductive tract organs were divided into accessory gland, testis, and seminal vesicle including the ejaculatory duct. Aqueous extracts of the seminal vesicle reduced receptivity of females immediately following injection, while aqueous extracts of the accessory gland reduced receptivity at the second day. The results suggest that the components of Fraction II existed in the seminal vesicle, and those of Fraction III in the accessory gland. The results of the present and the previous studies in Callosobruchus chinensis, a species closely related to C. maculatus, were compared and are discussed from the viewpoint of the significance of ejaculation in the two species.  相似文献   

19.
The fatty acids and sphingosine bases from major placenta gangliosides (NeuAcLacCer, IV3NeuAc-nLc4Cer, VI3NeuAc-nLc6Cer, (NeuAc)2LacCer, II3IV3(NeuAc)2Gg4Cer and VI3NeuAc, IV6(II3NeuAc-nLcNAc)-nLc6Cer) were studied. The C18-sphingenine was shown to be present in all ganglioside fractions; fraction GD1a contained, in addition, C20-sphingenine. Saturated fatty acids were identified as major fatty acid fragments. The content of long-chain acids (22-25 C-atoms) in the monosialogangliosides was much higher than that in disialogangliosides.  相似文献   

20.
The full assignment of 1H and 13C NMR signals of galactosylceramide 3-sulfate (galactosyl sulfatide) and 1H signals of galactosylceramide 6-sulfate was achieved by using 1H-1H DQF-COSY and 1H-13C heteronuclear COSY. Analyses were performed on a mixture of galactosyl sulfatides with four representative ceramide types consisting of a combination of non-hydroxy or 2-hydroxy fatty acids and sphingenine or 4D-hydroxysphinganine (trihydroxysphinganine) as the long-chain bases. The 1H and 13C NMR parameters of galactosyl sulfatide with 4-hydroxysphinganine as well as 13C signals of complex lipids with 4-hydroxysphinganine were elucidated for the first time. Not only sulfation of the galactosyl residue, but also modification of the aglycon, including hydroxylation of fatty acids and hydration of the double bond in sphingoid bases, altered the chemical shifts substantially. In addition, the unique long-range coupling constants, 4J(H,H) and 5J(H,H), in the galactosyl residue of galactosyl sulfatide could be determined.  相似文献   

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