首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
  • 1.1. The metabolism of inositol (Ins)-containing phospholipids and inositol phosphates has been studied by following the incorporation and distribution of myo-[3 H]Ins in metabolically active electrocytes from the electric ray Discopyge tschudii.
  • 2.2. The apparent initial rate of myo-[3H]Ins incorporation into total phosphoinositides was ca 8.2 fmol/mg protein/hr. Phosphatidylinositol (Ptdlns) displayed the highest levels of labelling. Lithium inhibited this incorporation probably by limiting the recycling of myo-[3H]Ins from [3H]Ins-monophosphate.
  • 3.3. The formation of water-soluble products of phosphoinositides between 7 and 24 hr was 4.1 ± 0.2, 0.4 ± 0.2 and 3.0 ± 1.0 fmol/μmmol total lipid phosphorus for myo-[3H]InsP, -InsP2 and Ins-P3 respectively.
  • 4.4. Lithium ions are shown to modulate phosphoinositide synthesis and Ins-phosphate accumulation. Ins-mono-, bis- and tris-phosphate production was enhanced 5-, 3- and 2-fold by Li +.
  • 5.5. The above results suggest the participation of a C-type phospholipase and of Li-sensitive phosphatases in the modulation of phosphoinositide metabolism in the electrocyte.
  相似文献   

2.
  • 1.1. A maximum rate of dolichyl phosphate [14C]glucose synthesis from 55-day embryos was achieved at 16nM concentration of exogenous dolichyl phosphate and exceeded about 3 times that without addition of dolichyl phosphate.
  • 2.2. The highest values of [14C]glucose incorporation from UDP-[14C]glucose into dolichyl phosphate [14C]glucose, dolichyl diphosphate [14C]Glc-oligosaccharides and proteins were reached at 5 min time point of incubation of liver microsomes both from embryos and sows.
  • 3.3. The radioactive incorporation into proteins was about 7-fold higher in liver microsomes from sows compared to that from embryos, probably due to the greater content of acceptor proteins in microsomes from sows.
  • 4.4. The enzymatic transfer of Glc3-oligosaccharide from a lipid carrier to endogenous protein acceptor in microsomes from pig embryonic and adult livers was considerably faster than the removal of glucose residues during the initial stages of processing of protein-bound oligosaccharides.
  • 5.5. One labelled compound was discovered in the Chcl3-Ch3Oh-H2O (1:1:0.3, by vol) extract after incubation of liver microsomes from embryos and sows with UDP-[14C]glucose. On the basis of its mobility on the chromatogram it appears to be GlcNAc2Man9Glc3.
  相似文献   

3.
  • 1.1. Indian River male broiler chickens growing from 7 to 28 days of age were fed diets containing 12, 18, 24 and 30% protein + 0 or 1 mg triiodothyronine (T3)/kg of diet to study energetic costs of lipogenesis and the use of various substrates for in vitro lipogenesis.
  • 2.2. De novo lipid and CO2 production were determined in the presence of [1-14C]pyruvate, [2-14q]pyruvate, [3-14C]pyruvate, [2-14C]acetate and [U-14C]alanine.
  • 3.3. Oxygen consumption was determined in mitochondrial preparations to estimate the energetic costs in expiants synthesizing lipid.
  • 4.4. Radiolabeled CO2 derived from [1-14C]pyruvate was used as an estimate of coenzyme A availability in liver expiants. Lipids derived from [2-14C]pyruvate, [2-14C]acetate and [U-14C]alanine estimate relative substrate efficiency.
  • 5.5. Labeled CO2 production from [1-14C]pyruvate was greatest in that group fed a 12% protein diet and least in the group fed a 30% protein diet.
  • 6.6. In addition, T3 increased CO2 production from [1-14C]pyruvate.
  • 7.7. The production of 14CO2 from the second carbon of pyruvate or acetate was increased by T3.
  • 8.8. The low-protein diet (12% protein) increased (P <0.05) lipogenesis.
  • 9.9. Adding T3 to the diets decreased carbon flux into lipid from all substrates, but increased CO2 production from all substrates without changing stage 3 and 4 respiration rates in mitochondrial preparations.
  • 10.10. These observations imply that coenzyme A availability may have regulated de novo lipogenesis in the present study.
  • 11.11. It was also concluded that previously noted effects of T3 on intermediary metabolism may involve metabolic pathways that do not involve changes in mitochondrial function.
  相似文献   

4.
  • 1.1. The generation of C2- and C3-deuterated l-lactate was monitored by 13C NMR in human erythrocytes exposed to d-[1-13glucose, d-[2-13C]glucose or d-te-13C]glucose and incubated in a medium prepared in D2O.
  • 2.2. The results suggested that the deuteration of the C1 of d-fructose 6-phosphate in the phosphoglucoisomerase reaction, the deuteration of the C1 of d-glyceraldehyde-3-phosphate in the sequence of reactions catalyzed by triose phosphate isomerase and aldolase and the deuteration of the C3 of pyruvate in the reaction catalyzed by pyruvate kinase were all lower than expected from equilibration with D2O.
  • 3.3. Moreover, about 40% of the molecules of pyruvate generated by glycolysis apparently underwent deuteration on their C3 during interconversion of the 2-keto acid and l-alanine in the reaction catalyzed by glutamate-pyruvate transaminase.
  • 4.4. The occurrence of the latter process was also documented in cells exposed to exogenous [3-13C]pyruvate.
  • 5.5. This methodological approach is proposed to provide a new tool to assess in intact cells the extent of back-and-forth interconversion of selected metabolic intermediates.
  相似文献   

5.
  • 1.1. The incorporation of myo-[2-3H]inositol into phosphatidylinositols was unmodified in brain cortex miniprisms from convulsant rats.
  • 2.2. However, the incorporation had increased by 300–400% in non convulsant rats which had received the same amount of lindane at a lower concentration.
  • 3.3. This result suggests that phosphatidylinositols are implicated in the convulsion syndrome.
  • 4.4. Experiments with lindane added in vitro were performed with both subchronically lindane intoxicated and untreated rats.
  • 5.5. The results show an interesting lack of parallelism.
  • 6.6. This might indicate the development of some resistance to the effects of lindane, possibly as the result of complex compensatory changes in inositol lipid biosynthesis.
  相似文献   

6.
  1. Download : Download high-res image (121KB)
  2. Download : Download full-size image
Highlights
  • 18O/16O labeling N-glycopeptide quantification for 40-kDa band in HCC and LC.
  • •MRM verification of aberrant N-glycopeptides in healthy-HBV-LC-HCC cascade.
  • •TPLTAN205ITK (H5N5S1F1) and (H5N4S2F1) of IgA2 change in liver diseases.
  • •Variation in two N-glycopeptides abundance not caused by protein concentration.
  相似文献   

7.
  • 1.1. Activity of topoisomerase I and incorporation of [3H]uridine and [14C]thymidine were monitored during light-induced sporulation of the slime mold Physarum polycephalun.
  • 2.2. A 4-fold transient increase of topoisomerase I activity but not of [3H]uridine or [14C]thymidine incorporation was observed after 42 hr of illumination with 6 hr impulses.
  • 3.3. The activity of topoisomerase I did not increase in the absence of light impulses. However, ca 5-fold increase of the activity was observed in dark when 100 μ M dibutyryl-cAMP was administered 12 hr before harvesting of plasmodia.
  • 4.4. Fluorodeoxyuridine and cycloheximide administered 36 hr after starting of the illumination cancelled the increase of the activity of topoisomerase I.
  • 5.5. After 7 days of the illumination, when fruiting bodies appeared, the activity of topoisomerase I dropped to about 15% of the initial value.
  相似文献   

8.
  • 1.1. The metabolic fate of 1-14C-acetate administered to the marine bivalve mollusc Mytilus edulis was investigated.
  • 2.2. The active incorporation of the label in 20:2 non-methylene-interrupted dienoic (NMID) fatty acids was found.
  • 3.3. Acetate incorporation patterns and specific radioactivity of mussel acids suggest that 22:2Δ7,13 and 22:2/gD7,15 arose by C2 elongation of 20:2Δ5,11 and 20:2Δ5,13 respectively.
  • 4.4. The proposed pathway of NMID fatty acid biosynthesis in molluscs is discussed.
  相似文献   

9.
  • 1.1. In vivo incorporation into body lipids and breast muscle proteins from l-[U-14C]leucine was studied in genetically lean or fat male chickens, fed or starved, 1 or 24 hr after intraperitoneal injection.
  • 2.2. Lipogensis and portein synthesis from labelled leucine were significantly higher in fat chickens than in lean birds, particularly in those in the fed state.
  • 3.3. Radioactivity in the free amino acid pool was greater in fat birds irrespective of the nutritional state.
  • 4.4. However, utilization of injected l-[U-14C]leucine for lipogenesis was no more than 2%.
  相似文献   

10.
  • 1.1. The effect of incorporating D2O into the incubation medium on glycolysis and gluconeogenesis by hepatocytes from fasted rats was examined.
  • 2.2. The substitution by heavy water, D2O, at concentrations from 10 to 40%, stimulated glucose uptake, lactate production and CO2 yields from glucose. At 10 mM glucose, 40% D2O doubled glucose uptake, increased CO2 production by 40%, and increased lactate production by 350%.
  • 3.3. The stimulation of lactate production decreased at higher glucose concentrations, but was still substantial even at 80 mM glucose.
  • 4.4. There was no effect on CO2 production above glucose concentrations of 30 mM.
  • 5.5. Ten percent D2O showed little inhibition of lactate uptake, its oxidation and gluconeogenesis. At 40% D2O the inhibition ranged from 10 to 20%.
  • 6.6. No effect of D2O on the rate of glucokinase or glucose-6-phosphatase was observed.
  • 7.7. The concentration of fructose, 2,6-P was not affected by D2O
  相似文献   

11.
  • 1.1. The present study was designed to investigate the effect of melatonin on the proliferation of normal lymphocytes and certain T-lymphomas and myelomas under in vitro conditions.
  • 2.2. The results revealed that administration of 200 μM melatonin inhibited significantly the incorporation of [3H]thymidine into both normal mouse and human lymphocytes and T-lymphoblastoid cell lines.
  • 3.3. On the contrary, melatonin provoked an increase of myeloma cell proliferation.
  • 4.4. The influence of melatonin on hybridoma cell lines was negligible.
  • 5.5. Collectively, these data demonstrated that the chief pineal indole affect selectively the processes of lymphoblastoid cell growth.
  相似文献   

12.
  • 1.1. The fatty acid composition of the triglyceride fraction of mink milk sampled during mid-lactation (day 28 post partum) from two nursing mink was compared to that of plasma samples and to the fatty acid composition of the feed rations used.
  • 2.2. Chemical analysis of the triglyceride composition of mink milk demonstrated only minute concentrations of fatty acids with a chain length below C14.
  • 3.3. The saturated C16:0- and C18:0-unit fatty acids in mink milk made up for 24–40% of the total amount of fatty acids extracted, the remainder being represented by mono and polyunsaturated long-chain (C16-C24) fatty acids.
  • 4.4. Preliminary in vitro experiments proved the incorporation of14C-labelled glucose, acetate or palmitate into triacylglycerols in cultures of mink mammary tissue to be linear for at least 2 hr.
  • 5.5. The in vitro capacity for de novo fatty acid synthesis in mink mammary tissue using 14C-labelled glucose or acetate was low, i.e. ranging from 0.096–0.109 nmol/g (fresh tissue)/min, and amounted to only about 5% of that obtained in the case of [14C]palmitic acid incubation.
  • 6.6. Following 14C-labeIled acetic or palmitic acid incubation of mink mammary tissue neither desaturation nor chain elongation was observed.
  • 7.7. In response to long-term feeding on rations with two different sources of animal fat (F = fish oil or L = lard) the influence of compositional changes in dietary neutral lipids on the fatty acid composition of the lipids of mink milk is discussed.
  相似文献   

13.
  • 1.1. Subcellular distribution of (NA+, K+-ATPase and ouabain-insensitive ATPase (Mg2+-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
  • 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
  • 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
  • 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.
  • 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
  • 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P3 from the posterior gills.
  • 3.(c) No activation occurs with the fractions P3 as well as P1 or P2 (not shown) from anterior gills of fresh water crab.
  • 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
  • 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
  • 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.
  相似文献   

14.
  • 1.1. Recently we described the isolation of the β-interferon receptor [Zhang et al. (1986) J. biol. Chem. 261, 8017–8021]. A highly purified product was obtained but in low quantities.
  • 2.2. The use ofbiotinylated β-interferon as a ligand represents an alternate approach to receptor isolation.
  • 3.3. We have prepared and characterized the derivatives N-(biotinyl)- and N-(biotinyl-ϵ-aminocaproyl)-recombinant human [Ser17-interferon β (B- and BC-recHulFNβ).
  • 4.4. Biotin incorporation does not result in any loss of antiviral activity, demonstrating the recognition of the derivative by the cell receptor.
  • 5.5. The biotinylated recHuIFNβ binds specifically and reversibly to succinoylavidin or guanidine thiocyanate-stripped succinoylavidin linked to a Sepharose matrix.
  • 6.6. Comparison of the competition curves obtained with [14C]biotin and [3H]biotinyl recHuIFN, in the presence of increasing concentrations of biotin suggests that the IFN moiety of the derivative has little effect on the affinity of biotin for avidin.
  • 7.7. Biotinylated recHuIFNβ derivatives represent useful probes for the β-IFN receptor.
  相似文献   

15.
  • 1.1. Subcellular fractions of rat liver were assayed for PLA2 activity.
  • 2.2. The PLA2 assay measures the release of [3 H]oleic acid from phospholipids, using labeled E. coli as substrate.
  • 3.3. Nuclear fractions contained PLA2 activity, which was Ca2+ dependent and could not be explained from mitochondrial, microsomal or plasma membrane contamination.
  • 4.4. The Vmax value of nuclear PLA2 is 0.30 ± 0.04 pmol oleic acid/min/mg protein; its Km value is 0.86±0.12μM, similar to that of mitochondrial PLA2.
  • 5.5. We conclude that rat liver nuclei contain PLA2 activity.
  相似文献   

16.
  • 1.1. A series of diesters of isohematoporphyrin (isoHp), from dimethyl to dioctyl were prepared according to Rimington et al. (1989b). Their optical absorption, fluorescence spectra and high performance liquid chromatography (HPLC) retention times were recorded.
  • 2.2. A plot of HPLC retention time against number of C atoms in the alcohol used for esterification was approximately linear at first then rising steeply from diamyl to diocyi ester, whether a gradient elution was used or only methanol: water, 95/5, at pH 7.5.
  • 3.3. Preparation of the diethers of isoHp was much more difficult than that of the corresponding derivatives of hematoporphyrin (Hp). Several different methods were investigated, varying both times and temperatures.
  • 4.4. These methods included reaction of isoHp or its demethyl ester with
    • 4.1.(i) a bromoalkane in presence of anhydrous K2CO3;
    • 4.2.(ii) reaction with bromoalkane and Ag2O;
    • 4.3.(iii) reaction of brominated-isoHp, prepared by using thionylbromide, with the selected alcohol, or corresponding sodium alcoholate;
    • 4.4.(iv) heating of isoHp alone with an alcohol containing 20% (w/v) H2SCO4 (temp. range from 45° to 118°C),
    • 4.5.(v) refluxing as in (iv) at the b.p. of the alcohol; and
    • 4.6.(vi) carrying out this reaction in refluxing ethyleneglycoldimethyl ether (b.p. 85°C) or diethyleneglycoldimethyl ether (b.p. 155°C).
  • 5.5. Some diether formation was observable by all these methods but yields were small, a considerable quantity of unreacted isoHp and other products remaining.
  • 6.6. Examined by HPLC, the diethers consistently afforded a forked peak which on thin layer chromatography was only resolved into two very closely associated bands by a solvent mixture carefully selected for development.
  • 7.7. On elution these materials had virtually identical optical absorption and fluoresence spectra.
  • 8.8. The nature of the association is discussed, atropisomers (Gottwald and Ullman, 1969) and possible stacked monomer: dimers (Abraham et al., 1963) being considered as possibilities.
  相似文献   

17.
  • 1.1. We report for the first time on the production and characterization of antibodies against a naturally occurring tetrahydroisoquinoline, namely salsolidine (6,7-dimethoxy-1-methyl-1,2,3,4-tetrahydroisoquinoline).
  • 2.2. Immunogen synthesis was carried out by coupling the hapten salsolidine to bovine serum albumin (BSA) as carrier protein on the basis of reductive amination.
  • 3.3. By immunization of rabbits with salsolidine-BSA conjugate antisalsolidine antibodies were produced.
  • 4.4. At a final dilution of 1:1700 the highest-litre antiserum bound 35% of 0.21 pmol [3H] salsolidine. This antiserum was used to develop a radioimmunoassay for salsolidine.
  • 5.5. Cross-reactivity studies revealed a high specificity of the antiserum to the hapten.
  • 6.6. The antibodies had a high affinity to salsolidine (Ka = 1.5 × 109 M−1).
  • 7.7. Standard curves covered a measuring range of 0.5–70 pmol/tube and the detection limit was found to be 0.27 pmol/tube.
  相似文献   

18.
  • 1.1. The fatty acylation of mucus glycoprotein nascent peptides was investigated using [3H]palmitic acid and [35S]methionine-labeled peptidyl-tRNA of rat gastric mucous cells.
  • 2.2. The mucus glycoprotein peptidyl-tRNA fraction was found to contain covalently bound palmitic acid in its complexes.
  • 3.3. RNase digestion of the mucus glycoprotein peptidyl-tRNA released [3H]palmitic acid labeled peptides which, on SDS-polyacrylamide gel, separated into a multitude of bands ranging in size from 2000 to 60,000 Da.
  • 4.4. The analyses of low molecular weight peptides revealed that palmitic acid was present in methionine-labeled peptides containing 30–43 amino acids and those of 18–25 amino acids or larger devoid of methionine, but was not identified in methionine-labeled peptides containing 10–15 amino acids.
  • 5.5. The results indicate that the N-terminal fatty acylation of mucus glycoprotein nascent peptides is a cotranslational process which is occuring in an immediate vicinity of the signal peptide fragment.
  相似文献   

19.
  • 1.1. Adenylylation, a posttranslational modification of proteins, was investigated in saponin-permeabilized acinar cells of the rat parotid gland.
  • 2.2. When cells were incubated with [2,8-3H]ATP, several proteins, including a 26 kDa protein in the particulate fraction, were labeled.
  • 3.3. Upon incubation of cells with [α-32P]ATP in the presence of cAMP and 3-isobutyl-lmethylxanthine, 32P-labeling of the 26 kDa protein was observed.
  • 4.4. After treatment with snake venom phosphodiesterase, [32P]AMP was released from the 26kDa protein. Such release was not observed when cells were labeled with [γ-32P]ATP.
  • 5.5. The 32P-labeling pattern of proteins with [α-32P]ATP was clearly different from that with [adenylate-32P]NAD+.
  • 6.6. The results suggest that the 26 kDa protein is one of the adenylylation substrates in rat parotid acinar cells.
  相似文献   

20.
  • 1.1. High levels of type I collagen mRNA and [3H]proline incorporation into collagenase digestable protein by MC3T3-E1 cells were detected during the first 7 days of culture, after which they declined.
  • 2.2. Type I collagen gene expression was stimulated by TGF-β in the early culture stage when the collagen gene expression was fully functioning.
  • 3.3. However, these stimulatory effects disappeared at the differentiation stages. Although collagen gene expression was stimulated by TGF-β (2.0 ng/ml) in early culture, collagen synthesis in medium was not.
  • 4.4. This study shows that collagen synthesis and collagen gene expression were affected by the state of differentiation in MC3T3-E1 cells and that the rate of stimulation by TGF-β in collagen gene expression decreased over time in culture.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号