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1.
Labelled shikimic acid was efficiently incorporated into the aniline moiety of N-(γ-L-glutamyl)-4-hydroxyaniline, a characteristic aromatic compound of the common mushroom, Agaricus bisporus. Incubations with [3-3H]- and [1,6-14C]shikimic acid clearly proved that the amination of shikimic acid occurs at its 4-position during the biosynthesis of N-(γ-L-glutamyl)-4-hydroxyaniline.  相似文献   

2.
This paper describes the transfer of tritium from [2-3H]xylitol or (1R)-[1-3H]ethanol into lactate in cells from fed rats either untreated or triiodothyronine-treated. The labelling pattern of lactate during the metabolism of [2-3H]xylitol or (1R)-[1-3H]ethanol follows the equation L = K(1?e?tτ) (μmol tritium/μmol lactate). The yield in lactate together with the minimum value of the total flux of reducing equivalents are used to estimate the specific radioactivity of NADH. We have calculated the lactate dehydrogenase-catalysed oxidation rate of NADH from the experimental values of lactate labelling and the specific radioactivity of NADH. We found the calculated flux of reducing equivalents from NADH to pyruvate to be of the same order of magnitude whether labelled ethanol or labelled xylitol was metabolized. We found the flux to be only a few percent of the maximal activity of lactate dehydrogenase. The results obtained suggest that the cytoplasm can be regarded as one compartment, containing a single pool of NAD(H).  相似文献   

3.
Agaricus bisporus contains novel aromatic compounds. By incubation of the mushroom with [G-14 C] shikimic acid, the radioactivity was incorporated into tyrosine, phenylalanine and several unidentified metabolites. The most radioactive metabolite in the stipe and the cap was identified as N-(γ-L-glutamyl)-4-hyrroxyaniline. The radioactivity was proved to be localized in the 4-hydroxyaniline moiety of this compound.  相似文献   

4.
2-Deoxy-D-glucoside-2-sulphamate sulphohydrolase was extracted from human liver and purified 40 000-fold by a simple four column procedure. The purification was followed using a specific substrate isolated from an acid hydrolysate of heparin, O-(α-2-sulphamino-2-deoxy-D-glucopyranosyl)-(1→3)-L-[6,3H]idonic acid. Only one form of the enzyme was seen on either ion exchange chromatography or isoelectric focussing, with a pI of 6.8. The apparent Mr of the haloenzyme as determined by gel filtration was 190 000 ± 20 000. Two other larger Mr protein peaks observed on gel filtration appear to be an inactive dimer of the 190 000 dalton peak and a larger aggregate near the exclusion limit of the column. On polyacrylamide disc gel electrophoresis in sodium dodecyl sulphate, with or without prior reduction, each protein peak from the gel filtration column electrophoreced as a single major band with an apparent Mr corresponding to 55 000 ± 6000.  相似文献   

5.
Isolated frog (RanaPipiens) retinas were labeled in the dark with either [32P]PO4-orthophosphate or myo-[2-3H]inositol for 2.5–4 hrs. After washing the retinas with cold buffer, they were exposed to brief flashes of light (5 secs or 15 secs) and their rod outer segments isolated. Upon separation of labeled phospholipids, a specific decrease in label in phosphatidylinositol 4,5-bisphosphate was observed, whereas there was no significant effect on the labeling of phosphatidylinositol 4-phosphate, phosphatidylinositol, or phosphatidic acid. These results are indicative of a light-activated phosphatidylinositol 4,5-bisphosphate-specific phospholipase C in frog rod outer segments.  相似文献   

6.
Joël Lunardi  Pierre V. Vignais 《BBA》1982,682(1):124-134
(1) N-4-Azido-2-nitrophenyl-γ-[3H]aminobutyryl-AdoPP[NH]P(NAP4-AdoPP[NH]P) a photoactivable derivative of 5-adenylyl imidodiphosphate (AdoPP[NH]P), was synthesized. (2) Binding of 3H]NAP4-AdoPP[NH]P to soluble ATPase from beef heart mitochrondria (F1) was studied in the absence of photoirradiation, and compared to that of [3H]AdoPP[NH]P. The photoactivable derivative of AdoPP[NH]P was found to bind to F1 with high affinity, like AdoPP[NH]P. Once [3H]NAP4-AdoPP[NH]P had bound to F1 in the dark, it could be released by AdoPP[NH]P, ADP and ATP, but not at all by NAP4 or AMP. Furthermore, preincubation of F1 with unlabeled AdoPP[NH]P, ADP, or ATP prevented the covalent labeling of the enzyme by [3H]NAP4-AdoPP[NH]P upon photoirradiation. (3) Photoirradiation of F1 by [3H]NAP4-AdoPP[NH]P resulted in covalent photolabeling and concomitant inactivation of the enzyme. Full inactivation corresponded to the binding of about 2 mol [3H]NAP4-AdoPP[NH]Pmol F1. Photolabeling by NAP4-AdoPP[NH]P was much more efficient in the presence than in the absence of MgCl2. (4) Bound [3H]NAP4-AdoPP[NH]P was localized on the α- and β-subunits of F1. At low concentrations (less than 10 μM), bound [3H]NAP4-AdoPP[NH]P was predominantly localized on the α-subunit; at concentrations equal to, or greater than 75 μM, both α- and β-subunits were equally labeled. (5) The extent of inactivation was independent of the nature of the photolabeled subunit (α or β), suggesting that each of the two subunits, α and β, is required for the activity of F1. (6) The covalently photolabeled F1 was able to form a complex with aurovertin, as does native F1. The ADP-induced fluorescence enhancement was more severely inhibited than the fluorescence quenching caused by ATP. The percentage of inactivation of F1 was virtually the same as the percentage of inhibition of the ATP-induced fluorescence quenching, suggesting that fluorescence quenching is related to the binding of ATP to the catalytic site of F1.  相似文献   

7.
Heparin was converted by treatment with nitrous acid primarily into sulfated disaccharides. The mixture of disaccharides was reduced with sodium boro[3H]hydride and the disaccharides were purified by preparative paper electrophoresis and paper chromatography. Four disaccharides were obtained. On the basis of their paper electrophoretic mobilities and the products formed at intermediate stages of their acid hydrolysis, the disaccharides were identified as 4-O-(2-O-sulfo-α-l-idopyranosyluronic acid)-6-O-sulfo-2,5-anhydro-d-mannitol, 4-O-(2-O-sulfo-α-l-idopyranosyluronic acid)-2,5-anhydro-d-mannitol, 4-O-(α-l-idopyranosyluronic acid)-6-O-sulfo-2,5-anhydro-d-mannitol, and 4-O-(β-d-glucopyranosyluronic acid)-6-O-sulfo-2,5-anhydro-d-mannitol. The purified disaccharides were used as standards in the development of a high-performance liquid chromatography procedure for their separation and quantitation on a Partisil-10 SAX anion-exchange column. The three monosulfated disaccharides were resolved by isocratic elution with 40 mm KH2PO4. The KH2PO4 concentration was tehn increased to 400 mm to elute the disulfated disaccharide. Column effluents were collected in 12-ml fractions, and the recovery of each 3H-labeled product was determined by scintillation counting. When sodium boro-[3H]hydride with a specific activity of 315 mCi/mmol was used in the reduction of the heparin deamination products, the disaccharides gave 28,500 cpm/nmol in the effluent peaks. Quantitative recoveries of the 3H-disaccharides were obtained. It was demonstrated that the method developed using the purified disaccharides gave reproducible and quantitative results in direct assays of aliquots of boro[3H]hydride-reduced heparin deamination mixtures.  相似文献   

8.
In vivo biosynthesis of -linolenic acid in plants   总被引:6,自引:0,他引:6  
[1-14C]acetate was readily incorporated into unsaturated fatty acids by leaf slices of spinach, barley and whole cells of Chlorellapyrenoidosa and Candidabogoriensis. In these systems the [14C] label in newly synthesized oleate and linoleate was approximately equally distributed in the C1–9 and the C10–18 fragments obtained by reductive ozonolysis of these acids, whereas in a-linolenic acid over 90% of the total [14C] was localized in the C1–9 fragment. While [1-14C]oleic acid was converted by whole cells of Chlorella to [1-14C]linoleic and [1-14C]linolenic acids, [U-14C]oleic acid yielded [U-14C]linoleic acid but a-linolenic acid was labeled only in the carboxyl terminal carbon atoms. When spinach leaf slices were supplied with carboxyl labeled octanoic, decanoic, dodecanoic, tetradecanoic and octadecanoic acids, only the first three acids were converted to a-linolenic acids while the last two acids were ineffective. Thus we suggest that (a) linoleic acid is not the precursor of a-linolenic acid and (b) 12:3(3, 6, 9) is the earliest permissible trienoic acid which is then elongated to a-linolenic acid.  相似文献   

9.
A method was developed for quantitative determination of 5α,7α-dihydroxy-11-ketotetranor-prostane-1,16-dioic acid, the major urinary metabolite of prostaglandins F and F in man. The method was based on the use of the O-methyloxime derivative of [5β-3H; 10,10,12,12-2H4]5α,7α-dihydroxy-11-ketotetranor-prostane-1,16-dioic acid as internal standard and determination of ratios between unlabeled and deuterium-labeled molecules by multiple-ion analysis. Excretion values found for healthy human subjects were: males, 10.8–59.0 μg24 hr (n = 10, mean value, 24.0 ± 17.2 (SD) μg) and females, 7.6–13.6 μg24 hr (n = 10, mean value, 10.5 ± 2.1 (SD) μg).  相似文献   

10.
(22S)-[22-3H1]-Cholesterol was incubated with an adrenocortical preparation and the isolated (22R)-[22-3H1]-22-hydroxycholesterol had a small loss of radioactivity, proving that direct replacement of the hydrogen from the now hydroxylated position occurred.In addition [1-3H1]-4-methylpentanol was isolated, which also had incurred a relatively small loss of its specific activity, thereby excluding (20R)-3β,20-dihydroxycholest-5-en-22-one as an important metabolite in the degradation of cholesterol to pregnenolone by adrenal tissue.  相似文献   

11.
As part of a program to synthesize the ceramide trisaccharide (1) related to Fabry's disease, methyl 4-O-(4-O-α-d-galactopyranosyl-β-d-galactopyranosyl)-β-d-glucopyranoside (12) was prepared. Methyl β-lactoside (2) was converted into methyl 4-O-(4,6-O-benzylidene-β-d-galactopyranosyl)-β-d-glucopyranoside (4). Methyl 2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-β-d-galactopyranosyl)-β-d-glucopyranoside (7) was synthesized from 4 through the intermediates methyl 2,3,6-tri-O-benzoyl-4-O-(4,6-O-benzylidene-2,3-di-O-benzoyl-β-d-galactopyranosyl)-β-d-glucopyranoside (5) and methyl 2,3,6-tri-O-benzoyl-4-O-(2,3-di-O-benzoyl-β-d-galactopyranosyl)-β-d-glucopyranoside (6). The halide-catalyzed condensation of 7 with 2,3,4,6-tetra-O-benzyl-d-galactopyranosyl bromide (8) gave methyl 2,3,6-tri-O-benzoyl-4-O-[2,3,6-tri-O-benzoyl-4-O-(2,3,4,6-tetra-O-benzyl-α-d-galactopyranosyl)- β-d-galactopyranosyl]-β-d-glucopyranoside (10). Stepwise deprotection of 10 led to 12, the methyl β-glycoside of the trisaccharide related to Fabry's disease.  相似文献   

12.
A low-molecular-weight interferon-mediated ribosome-associated inhibitor of reovirus mRNA translation was purified from the 0.5 M KCl ribosomal salt-wash fraction of mouse L929 cells. The inhibitor possessed nucleolytic activity with reovirus [3H]mRNA as a substrate. Loss of translational inhibitory activity correlated with the thermal inactivation of the nuclease. A low-molecular-weight (<10K) component present in the Bio-Gel P150 chromatography fractions which contained the interferon-mediated nucleolytic activity was labeled in vivo with [14C]valine; a smaller component present in the same fractions was phosphorylated in vitro with [γ-32P]ATP. The <10K components were resolved from ~50K, ~30K and ~20K phosphorylatable proteins associated with ribosomes that possess the interferon-mediated inhibitor(s) of viral mRNA translation.  相似文献   

13.
Portions of crude homogenates of etiolated wheat seedlings incubated with Mg-protoporphyrin IX and S-adenosyl-L-methionine and then added to other portions of the same crude homogenates that were pretreated with [1-3H]ethanol and yeast alcohol dehydrogenase provided, after a short reaction period, 3H-labeled Mg-protoporphyrin IX monomethyl ester. The 3H-labeled Mg-protoporphyrin IX monomethyl ester thus obtained was shown to contain the 3H in one reduced (to ethyl) vinyl side-chain. Subsequently, 3H-labeled Mg-monoethyl-(monodivinyl)-protoporphyrin IX monomethyl ester was obtained when Mg-protoporphyrin IX monomethyl ester and [3H]NADH were added to dialyzed crude homogenates of etiolated wheat seedlings. Insignificant amounts of 3H were incorporated into poprhyrin substrates when Mg-2,4-divinylpheoporphyrin a5 or [3H]NADPH were substituted in reaction mixtures for Mg-protoporphyrin IX monomethyl ester or [3H]NADPH, respectively. The results of these and further experiments suggest that an NADPH-dependent enzyme in the crude homogenates of etiolated wheat seedlings was capable of catalyzing the reduction to ethyl of one vinyl side-chain of Mg-protoporphyrin IX monomethyl ester. These findings suggest that the 4-vinyl side-chain reductive reaction likely occurs after the biosynthesis IX monomethyl ester, but before isocyclic ring formation in the pathway to chlorophyll a.  相似文献   

14.
A novel leukotriene formed by transpeptidation of leukotriene E   总被引:2,自引:0,他引:2  
A new leukotriene 5(S)-hydroxy-6(R)-S-γ-glutamylcysteine-7,9-trans-11,14-cis-eicosatetraenoic acid (leukotriene F4) was isolated after incubating leukotriene E4 with γ-glutamyltranspeptidase and glutathione. Leukotriene F4 induced contractions of the isolated quinea pig ileum and was less potent in this respect than leukotriene E4.  相似文献   

15.
Partial acid hydrolyzates of the extracellular polysaccharide from Porphyridiunm cruentum yield three disaccharides and two uronic acids. These constitute all of the uronic acid in the polymer. The novel disaccharides are 3-O-(α-D-glucopyranosyl- uronic acid)-L-galactose, 3-O-(2-O-methyl-ca-glucopyranosyluronic acid)-D- galactose, and 3-0-(2-0-methyl-a-D-glucopyranosyluronic acid)-D-glucose. The polyanion of high molecular weight contains D- and L-galactose, xylose, D-glucose, D-glucuronic acid and 2-O-methyl-D-glucuronic acid, and sulfate in molar ratio (relative to D-glucose) of 2.12:2.42:1.00:1.22:2.61. Preliminary periodate-oxidation studies suggest that the hexose and uronic acids are joined to other residues by ( 1→3) glycosidic linkages. About one-half of the xylose residues are (1→3)-linked.  相似文献   

16.
The reference standards methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10b) and corresponding precursors 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11b) were synthesized from methyl crotonate and 3-amino-4-methylbenzoic acid in multiple steps with moderate to excellent yields. The target tracer [11C]methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([11C]10a) and [11C]methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([11C]10b) were prepared from their corresponding precursors with [11C]CH3OTf under basic condition through O-[11C]methylation and isolated by a simplified solid-phase extraction (SPE) method in 50–60% radiochemical yields at end of bombardment (EOB) with 185–555 GBq/μmol specific activity at end of synthesis (EOS).  相似文献   

17.
Results are presented on the stability of high specific activity [uridylate-5,6-3H]polyuridylic acid and [adenylate-2,8-3H]polyadenylic acid stored under various conditions. Polyacrylamide disc gel electrophoresis in the presence of SDS was used to assess qualitatively the change in molecular weight distribution of the polynucleotides stored under different conditions. Products stored for a period of months in ethanol; water solution [1:1, vv] were found to have a significantly slower rate of decomposition than polynucleotides stored in frozen aqueous solution or as lyophilized solid.  相似文献   

18.
Two analogs of N-acetylmannosamine, 2-acetamido-1,3,4,6-tetra-O-acetyl-2-deoxy-d-mannopyranose (Ac4-NAcMan) and the 2-trifluoroacetamido derivative (Ac4F3-NAcMan), were synthesized as potential inhibitors of the formation of sialic acid-containing glycoconjugates and were examined for their ability to modify the incorporation of N-[3H]acetylmannosamine into cellular glycoconjugates of Friend murine erythroleukemia cells. Ac4F3-NAcMan and Ac4-NAcMan inhibited cellular replication in suspension culture at concentrations of 0.02 and 0.08 mM, respectively. The cytotoxicity of Ac4-NAcMan was relatively reversible, whereas that produced by Ac4F3-NAcMan was not, as judged by measurement of the cloning efficiencies of cells exposed to these agents. The analogs inhibited incorporation of N-[3H]acetylmannosamine into ethanol-soluble and -insoluble materials. Separation of ethanol-soluble metabolites by HPLC demonstrated that Ac4F3-NAcMan caused accumulation of radioactivity from N-[3H]acetylmannosamine in CMP-N-acetylneuraminic acid (CMP-NeuNAc) equal to the decrease in macromolecular-bound 3H caused by this agent. In contrast, similar exposure to Ac4-NAcMan produced a large increase in the amount of radioactivity in ethanol-soluble N-acetylneuraminic acid while decreasing the amount of label from N-[3H]acetylmannosamine in cellular CMP-NeuNAc, suggesting that the analogs differ in their biochemical sites of action. Treatment of cells with either analog increased the amount of neuraminidase-hydrolyzable sialic acid-like material on the cell surface; this appeared to be due to the incorporation of the analogs into cellular glycoconjugates, since incubation of cells with 3H-labeled analogs resulted in the appearance of radioactivity in cellular ethanol-insoluble and neuraminidase-hydrolyzable material. Incubation of cells with Ac4-NAcMan labeled with 14C in the 4-O-acetyl group further demonstrated that incorporation occurred with approx. 50% retention of this substituent. Thus, both the amount and the nature of the surface sialic acid constituents of treated cells were altered, suggesting that these or similar analogs could potentially be used to modify cellular membrane function.  相似文献   

19.
Six acylated delphinidin glycosides (pigments 1-6) and one acylated kaempferol glycoside (pigment 9) were isolated from the blue flowers of cape stock (Heliophila coronopifolia) in Brassicaceae along with two known acylated cyanidin glycosides (pigments 7 and 8). Pigments 1-8, based on 3-sambubioside-5-glucosides of delphinidin and cyanidin, were acylated with hydroxycinnamic acids at 3-glycosyl residues of anthocyanidins. Using spectroscopic and chemical methods, the structures of pigments 1, 2, 5, and 6 were determined to be: delphinidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(acyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which acyl moieties were, respectively, cis-p-coumaric acid for pigment 1, trans-caffeic acid for pigment 2, trans-p-coumaric acid for pigment 5 (a main pigment) and trans-ferulic acid for pigment 6, respectively. Moreover, the structure of pigments 3 and 4 were elucidated, respectively, as a demalonyl pigment 5 and a demalonyl pigment 6. Two known anthocyanins (pigments 7 and 8) were identified to be cyanidin 3-(6-p-coumaroyl-sambubioside)-5-(6-malonyl-glucoside) for pigment 7 and cyanidin 3-(6-feruloyl-sambubioside)-5-(6-malonyl-glucoside) for pigment 8 as minor anthocyanin pigments. A flavonol pigment (pigment 9) was isolated from its flowers and determined to be kaempferol 3-O-[6-O-(trans-feruloyl)-β-glucopyranoside]-7-O-cellobioside-4′-O-glucopyranoside as the main flavonol pigment.On the visible absorption spectral curve of the fresh blue petals of this plant and its petal pressed juice in the pH 5.0 buffer solution, three characteristic absorption maxima were observed at 546, 583 and 635 nm. However, the absorption curve of pigment 5 (a main anthocyanin in its flower) exhibited only one maximum at 569 nm in the pH 5.0 buffer solution, and violet color. The color of pigment 5 was observed to be very unstable in the pH 5.0 solution and soon decayed. In the pH 5.0 solution, the violet color of pigment 5 was restored as pure blue color by addition of pigment 9 (a main flavonol in this flower) like its fresh flower, and its blue solution exhibited the same three maxima at 546, 583 and 635 nm. On the other hand, the violet color of pigment 5 in the pH 5.0 buffer solution was not restored as pure blue color by addition of deacyl pigment 9 or rutin (a typical flower copigment). It is particularly interesting that, a blue anthocyanin-flavonol complex was extracted from the blue flowers of this plant with H2O or 5% HOAc solution as a dark blue powder. This complex exhibited the same absorption maxima at 546, 583 and 635 nm in the pH 5.0 buffer solution. Analysis of FAB mass measurement established that this blue anthocyanin-flavonol complex was composed of one molecule each of pigment 5 and pigment 9, exhibiting a molecular ion [M+1] + at 2102 m/z (C93H105O55 calc. 2101.542). However, this blue complex is extremely unstable in acid solution. It really dissociates into pigment 5 and pigment 9.  相似文献   

20.
The syntheses of (±) 2α,6β-diethyl-7α-ethynyl-3α-(p-hydroxyphenyl)-trans-bicyclo[4.3.0]nonan-7β-ol (8), (±)2β,6β-diethyl-7α-ethynyl-3β-(p-methoxyphenyl)-trans-bicyclo[4.3.0]nonan-7β-ol (12) and (±) 2α,6β-diethyl-7α-ethynyl-3β-(p-hydroxyphenyl)-trans-bicyclo[4.3.0]nonan-7β-ol (18) and their derivatives, which are essentially B-seco-steroids having cis-anti-trans, cis-syn-trans and trans-anti-trans geometries have been carried out. A study of their antiimplantation activities (AI) and receptor binding affinities (RBA) show that trans-anti-trans compounds are biologically most potent, followed by the corresponding cis-anti-trans and cis-syn-trans compounds. The most potent compound 18 is active at 1 mg/kg in rats. Introduction of 7α-ethynyl group increases their AI activity; however, no significant effect on their RBA is observed.  相似文献   

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