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1.
Proteoglycans were extracted from porcine lungs with 4 M guanidinium chloride. The extract was subjected to associative density gradient centrifugation, and four equal fractions, labeled A1 through A4 from the bottom to the top of the gradient, were obtained. The pooled A1 fractions containing proteoglycan aggregates were further fractionated by dissociative density gradient centrifugation to yield four equal fractions labeled A1D1 through A1D4 from the bottom to the top of the gradient. These fractions were analyzed for their protein, uronic acid, glucosamine, galactosamine, hexose, and sialic acid content. The fraction A1D1 with the highest buoyant density had the highest content of uronic acid and galactosamine, and lowest content of protein, indicating the enrichment of proteoglycan monomers at the bottom of the dissociative density gradient. As the density of the gradient decreased, the protein, hexoses, and sialic acid content increased, whereas uronic acid and galactosamine content decreased. The amino acid analysis showed similar composition for all four fractions with aspartic acid, serine, glutamic acid, proline, glycine, alanine, valine, and leucine as the major constituent amino acids. No hydroxyproline was detected in any of the fractions. As the buoyant density of the fractions decreased, the aspartic acid content increased and glycine content decreased. 相似文献
2.
Distribution of Calretinin, Calbindin D28k, and Parvalbumin in Subcellular Fractions of Rat Cerebellum: Effects of Calcium 总被引:4,自引:0,他引:4
Abstract: The distribution of calretinin, calbindin D28k, and parvalbumin was examined in subcellular fractions prepared from rat cerebellum and analyzed by immunoblot. Calretinin was also quantified by radioimmunoassay. As expected, all three soluble, EF-hand calcium-binding proteins were predominantly localized in the cytosolic fraction. Calretinin and calbindin D28k were also detected in membrane fractions. Calretinin was more abundant in synaptic membrane than in microsomal fractions. The cerebellar microsomal fraction contained the greatest concentration of membrane-associated calbindin D28k. The association of calretinin and calbindin D28k with membrane fractions was decreased in samples prepared or incubated in low calcium. Quantification of calretinin in subcellular fractions of rat cerebellum revealed a greater amount of calretinin in cytosolic fractions prepared or incubated in low calcium and reduced amounts of calretinin in all membrane fractions incubated in low calcium with the exception of the mitochondrial fraction. These results imply that calretinin and calbindin D28k might have physiological target molecules that are associated with, or are components of, brain membranes. 相似文献
3.
The formation of oligoglucans linked to lipid during synthesis of beta-glucan by characterized membrane fractions isolated from peas. 总被引:3,自引:0,他引:3
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Membrane fractions were obtained from peas roots by using a method that permitted the isolation of a fraction rich in relatively intact dictyosome stacks. No chemical fixatives were used. The method involved incubation of the roots with cellulase, followed by gentle homogenization and sucrose-density-gradient fractionation of the homogenate. The fractions were characterized by electron microscopy. All fractions were enzymically active in incorporating glucose from UDP-glucose into water-insoluble glycolipids containing both single glucose residues and glucose oligosaccharides. Some or all of the linkages of glucose to lipid were through phosphate esters. A substance containing glucose oligosaccharides attached to or very strongly adsorbed on to protein was also formed. The membrane fractions also incorporated glucose from UDP-glucose into alkali-soluble and alkali-insoluble beta-glucans, which like the oligosaccharides contained beta(1leads to 3) and beta-(1leads to4) linkages. The distribution of the enzymic activities and the chemical properties of the lipid-linked and protein-linked oligosaccharides suggest that they may be intermediates in beta-glucan synthesis. The synthetic activity is associated with smooth-membrane vesicles which may be derived from the plasma membrane. 相似文献
4.
The separation of the mycobactins from Mycobacterium smegmatis by using high-pressure liquid chromatography. 总被引:1,自引:0,他引:1
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The family of mycobactins from Mycobacterium smegmatis were resolved into seven fractions by high-pressure liquid chromatography. This separation was by virtue of the differences in length and character of the long acyl substituents as shown by g.l.c. of the methyl esters of the isolated fatty acids from the fractions. As t.l.c. could also resolve the individual mycobactin fractions, it too must rely on the same differences to effect separation. As the lengths of the acyl chains were modulated by the growth conditions, a specific range of acyl groups may not be needed for mycobactin to function. This technique provides a simple means of rapidly characterizing crude mycobactins from all mycobacteria. 相似文献
5.
Soluble extracts of Plasmodium berghei were separated into 12 fractions following preparative disc electrophoresis in polyacrylamide gel. One or two protein bands were detected in each fraction by analytical disc electrophoresis. Similarly, one or two precipitinogens were generally detected in each of Fractions 1 through 11 by immunoelectrophoresis and by double immunodiffusion in agar gel, while the unfractionated extract contained 10 precipitinogens. Antisera produced in rabbits against each fraction each contained two or three (sometimes five) antiplasmodial precipitins demonstrable by immunoelectrophoresis. Serial fractions obtained in separate runs were closely similar to each other, although some degree of overlapping sometimes occurred between neighboring fractions. Glycoproteins were detected in all the fractions, but chiefly in Fractions 4 and 12. The bulk of the RNA in the extract was located in Fraction 4, while hemoglobin was usually confined to Fraction 6. The molecular weights of the soluble components of P. berghei range between 8000 and 130,000. 相似文献
6.
Abstract— The synthesis of γ-aminobutyric acid (GABA) in mouse brain was decreased by treatment of the animals with pyridoxal phosphate- γ-glutamylhydrazone, an inhibitor of glutamate decarboxylase in vivo. Under these experimental conditions the following parameters were studied: (1) the incorporation of labeled leucine in vivo , into protein of brain subcellular fractions; (2) the brain polysome profile; (3) the incorporation of labeled leucine into protein in vitro , in ribosomal preparations isolated from brain tissue. In other experiments, GABA synthesis was also decreased in brain cortex slices by preincubation with aminooxyacetic acid. The incorporation of [3 H]leucine or [14 C]leucine into protein in these slices was studied, and samples from the proteins were subjected to acrylamide-sodium dodecylsulfate gel electrophoresis. Radioactivity was counted in slices of the gel. The results of the experiments in vivo and in vitro indicate that the previously reported decrease of protein synthesis induced by an inhibition of GABA synthesis affects proteins of all subcellular fractions and all populations of protein as separated by gel electrophoresis. The polysome profile from brains of mice with decreased GABA synthesis was similar to that of control mice. This result differs from that found when brain protein synthesis is inhibited by dopamine and serotonin. 相似文献
7.
Up-Dong Yeo Jung-Yeun Han Yong-Eui Choi Woong-Young Soh Naoki Nakagawa Naoki Sakurai 《Journal of Plant Biology》1999,42(1):8-15
Non-embryogenic cells (NEC) and embryogenc cells (EC) were separated from cell clusters derived from the hypocotyl segments
of celery seedlings, which had been suspension-cultured in MS medium supplemented with 105 M 2,4-D. The EC formed globular embryos in medium without 2,4-D. The globular embryo developed through heart-shaped, torpedo
to cotyledonary embryos within 10 days. The EC and developing embryos were fractionated into symplastic [MeOH, hot water (HW),
starch (S)] and apoplastic [pectin, hemicellulose, TFA (trifluoroacetic acid)-soluble and cellulose] fractions. The EC contained
lower levels of sugar in the MeOH fraction and higher levels of starch than NEC. In the apoplastic fractions, there were no
differences of total sugar amounts between NEC and EC. Cellulose contents were about 10% of the wall polysaccharides. During
somatic embryogenesis, total sugar contents of the MeOH and HW fractions increased till the heart-shaped embryo stage, and
then decreased during the torpedo and cotyledonary embryo stages. The sugar contents of the starch, pectin, TFA-soluble, and
cellulose fractions did not change during the stages mentioned above. However, the hemicellulose substances remarkably increased
during embryogenesis, and then decreased as the development proceeded. The neutral sugar components of the hemicellulosic
fractions were analyzed. Arabinose increased markedly in EC to the globular embryo stage, but decreased as the development
proceeded. Galactose increased only at the torpedo and cotyledonary embryo stages. Xylose was present at lower levels in all
stages of embryogenesis than in the differentiated hypocotyl cell walls. These results suggest that there was a high turnover
of arabinogalactan polysaccharides during embryogenesis, and that xylan accumulated in the cell walls of differentiated cells 相似文献
8.
Mass transfer limitations severely impede the performance of bioreactions involving large molecules by gel-entrapped microorganisms. This paper describes a quantitative investigation of such diffusional limitations in agar gel membranes. Sucrose and commercial dextran fractions with (weight-average) molecular weights ranging from 10,000 to 2,000,000 Da were used as standard diffusants. For all tested solutes but sucrose, the values of the agar/water partition coefficients highlighted steric hindrance at the entrance of the membrane pores. The effective diffusivity of sucrose in agar was similar to that in water. All dextran fractions, however, displayed restricted diffusion in the agar membranes. Their effective diffusivities were a decreasing function of the agar content of the gel membrane (0.5, 1.0, or 1.5% w/v). The effective diffusivity in a given membrane decreased as the molecular weight of the diffusing molecule increased. T500 (ucbar|Mw = 470,000 Da) and ucbar|Mw = 1,950,000 Da) fractions were unable to diffuse through 1.0 or 1.5% agar membranes. The diffusion data did not agree with the classical (Renkin) model for a hard sphere diffusing through a cylindrical pore. These results are discussed in terms of gel and diffusant characteristics. 相似文献
9.
Human liver arylsulfatase A was resolved into six fractions by narrow pH range preparative isoelectric focusing. Analytical isoelectric focusing revealed that most enzyme fractions were composed of two adjacent charge isomers. Nevertheless, there was considerable enrichment of charge species which allowed a comparative study of selected properties. Except for the most cationic fraction, neuraminidase treatment converted enzyme in all fractions to the three most cationic species. The most electronegative enzyme species had the highest molecular mass being made up of 64-kDa subunits. As electronegativity decreased, there was concomitant decrease in molecular mass and increase in complexity of subunit composition. Two subunits--61 and 55 kDa--prevailed with increasing proportions of the smaller unit with loss of electronegativity. There was also an increasing amount of a 26-kDa fraction which became a substantial component of the most cationic subfraction. Only enzyme in the two fractions containing the largest and most anionic species were taken up by cultured fibroblasts at higher efficiency than unfractionated enzyme. It is suggested that processing or maturation of arylsulfatase A incurs stepwise removal of charge groups and/or peptide segments leading to smaller, less-charged enzyme species. 相似文献
10.
本研究采用酿酒酵母发酵的方法对灵芝胞外多糖进行了降解,并对其产物在表观粘度、分子量、多糖得率和含量及单糖组成和生物活性等方面进行了系统比较和分析。结果表明,灵芝发酵胞外液经酿酒酵母培养后,所得胞外液的表观粘度明显降低,其中多糖的分子量也随酵母培养时间的延长出现下降趋势,大分子多糖的分子量从3.55×10 6g/mol下降到1.93×10 6g/mol,低分子多糖的分子量从6.18×10 4g/mol下降到3.11×10 4g/mol。多糖得率和含量测定结果显示,经酵母培养后,灵芝胞外液中20%乙醇沉淀所得20E组分得率明显降低,从2.43g/L下降到0.98g/L,但该组分多糖含量均较高,达到70%以上;而70%乙醇沉淀所得70E组分得率明显增加,达到1.87g/L。单糖组成分析表明,20E组分主要由葡萄糖组成,70E组分主要由甘露糖组成。各组分均表现出较好的与Dectin-1受体结合激活NF-κB增强免疫的活性,且经酿酒酵母发酵24h所得70E组分的活性最好。 相似文献
11.
Separation of phthalate esters from bio-oil derived from rice husk by a basification-acidification process and column chromatography 总被引:1,自引:0,他引:1
Solid precipitate containing phthalate esters was obtained from rice-husk-derived oil through a basification-acidification process. After separation by column chromatography, the solid precipitate was divided into two mono-component fractions, two bi-component fractions and a tetra-component fraction. The major compounds of the five fractions were all consisted of phthalate esters. Especially, phthalate esters accounted for a proportion higher than 80% in both Fractions I and II. The generation and precipitation mechanisms of phthalate esters were proposed. Phthalate esters were considered to be derived from a series of complicated chemical reactions of small molecules in the biomass pyrolysis process, and precipitated from bio-oil by catalytic hydrolysis and esterification. 相似文献
12.
A N Klimov E D Poliakova L E Vasil'eva T V Denisenko E B Dizhe 《Biokhimii?a (Moscow, Russia)》1987,52(2):239-246
The effect of cholesterol diet on the rate of mevalonic acid biosynthesis from 1-14C acetyl-CoA, 2-14C malonyl-CoA and the incorporation of these substrates into sterols and bile acids in rabbit liver were studied. Simultaneously, the activities of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) and acetyl-CoA carboxylase and the biosynthesis of fatty acids from acetyl-CoA and malonyl-CoA were measured. Hypercholesterolemia was found to be concomitant with the inhibition of acetyl-CoA carboxylase activity only in cell-free (700 g) and mitochondrial fractions and slightly decreased the incorporation of acetyl-CoA and malonyl-CoA into fatty acids in the postmitochondrial fraction. The HMG-CoA reductase activity in all subcellular fractions except for the postmicrosomal one was inhibited under these conditions. A significant decrease of acetyl-CoA incorporation and an increase in malonyl-CoA incorporation into mevalonic acid in all liver fractions except for microsomal one were observed in rabbits with hypercholesterolemia. These data provide evidence for the existence of two pathways of mevalonic acid synthesis from the above-said substrates that are differently sensitive to cholesterol. Cholesterol feeding resulted in a decreased synthesis of the total unsaponified fraction including cholesterol from acetyl-CoA, malonyl-CoA and mevalonic acid. The rate of incorporation of these substrates into lanosterol was unchanged. All the indicated substrates (acetyl-CoA, malonyl-CoA, mevalonic acid) are precursors of bile acid synthesis in rabbit liver. Cholesterol feeding and the subsequent development of hypercholesterolemia resulted in bile acid synthesis stimulation, preferentially in the formation of the cholic + deoxycholic acids from these precursors. 相似文献
13.
The 30-50% ammonium sulfate fraction of the high speed supernatant (100,000 xg) of a rat lung homogenate is capable of catalysing the conversion of arachidonic acid into 8,11,12- and 10,11, 12-trihydroxyeicosatrienoic acids. This enzyme preparation was resolved through DEAE cellulose chromatography into three stages which were assayed with precursors specific for each stage. Thus in the first stage arachidonic acid is converted by 12-lipoxygenase into 12-hydroperoxy-5,8,10,14-eicosatetraenoic acid (12-HPETE) detected as the corresponding 12-hydroxy product (12-HETE). 12-HPETE in turn is converted into 8-hydroxy-11,12-epoxy-5,9,14-eicosatrienoic acid and 10-hydroxy-11,12-epoxy-5,8,14-eicosatrienoic acid. These epoxides are in turn selectively converted through an epoxide hydrase into the respective triols. While the first and third stages were carried out by distinct fractions from the DEAE columns, the second i.e. conversion of 12-HPETE into epoxides, was detected in all fractions as was the reduction of 12-HPETE into 12-HETE. 相似文献
14.
We previously showed that hyperoxia exerts oxidative stress on the rat cerebral cortex, and the protein levels of phospholipase C (PLC) -beta1 and -delta1, but not PLC-gamma1, were changed. Acrylonitrile (ACN) appears to induce astrocytomas through induction of oxidative stress on the rat brain selectively. This study compared hyperoxia or ACN treatments of rats with respect to lipid peroxidation and PLC levels in the heart and cerebral cortex. Treatment of rats with ACN promoted lipid peroxidation in the heart and cerebral cortex, the percent increase above control being greater in the cortex than heart. Hyperoxia did not cause significant increases in lipid peroxidation in the cerebral cortex or heart. In the ACN-treated cerebral cortex, significant increases in the PLC-beta1 and -delta1 in the cytosol, and PLC-gamma1 in the cytosolic and particulate fractions, and lysate were observed. In the rat heart, in which PLC-beta1 could not be detected, PLC-gamma1 and -delta1 were increased and decreased in the cytosolic and particulate fractions, respectively, by hyperoxia. In addition, the expression level of PLC-gamma1 was decreased in the lysate by the treatment. In the heart treated with ACN, there was no change in the level of PLC-gamma1, while PLC-delta1 was elevated in all fractions. These findings suggested that the expression levels of PLC isozymes are altered by hyperoxia and ACN, but there are apparent differences in these altered levels between the different levels of oxidative stress, and between the organs. 相似文献
15.
The peptides secreted by Tetrahymena cells into inorganic medium were chromatographed. Six fractions showing a marked enzyme-like activity were examined for influence on certain physiological parameters of Tetrahymena. The enzymatically active fractions increased the phagocytic activity of Tetrahymena and decreased its binding capacity for lectins and hormone (insulin), but enhanced insulin imprinting at primary interaction. It remains to be clarified whether these effects were due to the enzymatic or other components of the fractions investigated, or to lack of the compensatory influence of the fractions not studied. 相似文献
16.
Corpora lutea (CL) from Days 5, 10, and 15 after superovulation were enzymatically dispersed, and a portion of the cells were elutriated to obtain fractions enriched with small or large luteal cells. Mixed, small, and large luteal cell fractions were incubated with no treatment or with agonists or antagonists of cAMP (dbcAMP or Rp-cAMPS), protein kinase C (PKC; TPA or H-7), or calcium (A23187, EGTA, or A23187 + EGTA). The rate of contact-dependent gap junctional intercellular communication (GJIC) was evaluated by laser cytometry. Media were collected for progesterone (P(4)) radioimmunoassay, and luteal cells cultured with no treatment were fixed for immunocytochemistry or frozen for Western blot analysis. Luteal cells from each stage of the estrous cycle exhibited GJIC. The dbcAMP increased (P < 0.05) GJIC for all cell types across the estrous cycle. The Rp-cAMPS decreased (P < 0.05) GJIC for small luteal cells on Day 5 and for all cell types on Days 10 and 15. The TPA inhibited (P < 0.01), but H-7 did not affect, GJIC for all cell types across the estrous cycle. The A23187 decreased (P < 0.05) GJIC for large luteal cells touching only small or only large luteal cells, whereas A23187 + EGTA decreased (P < 0.05) GJIC for all cell types across the estrous cycle. For the mixed and large luteal cell fractions, dbcAMP increased (P < 0.05), but TPA and A23187 + EGTA decreased (P < 0.05), P(4) secretion. The A23187 alone decreased (P < 0.05) P(4) secretion by large, but not by mixed, luteal cells. For all days and cell types, the rate of GJIC and P(4) secretion were correlated (r = 0.113-0.249; P < 0.01). Connexin 43 was detected in cultured luteal cells by immunofluorescence and Western immunoblotting. Thus, intracellular regulators like cAMP, PKC, or calcium appear to regulate GJIC, which probably is an important mechanism for coordinating function of the ovine CL. 相似文献
17.
The isolated perfused rat lung was used as a model to study the possible hormonal regulation of lipid metabolism in the mammalian adult lung. Experimental diabetes, whether induced by alloxan or streptozotocin, decreased the incorporation of [U-14C]glucose into neutral lipids and phospholipids of both the surfactant fraction and the residual fraction of the lung by 60-80%. Glucose incorporation into phosphatidylcholine and phosphatidylglycerol is decreased in experimental diabetes in both the surfactant and residual fractions to a comparable degree. Glucose incorporation is decreased in both the fatty acid and the glycerophosphocholine moieties of phosphatidylcholine isolated from the surfactant and residual fractions. Insulin treatment of normal animals 30 or 15 min prior to perfusion resulted in an approximate doubling of the incorporation of glucose into the phosphatidylcholine and phosphatidylglycerol isolated from the surfactant and residual fractions of the lung. The incorporation of glucose into palmitic acid isolated from phosphatidylcholine was also shown to increase similarly. The results of these investigations indicate that insulin may play a role in regulating the synthesis of the important lipid components of the mammalian pulmonary surfactant complex. 相似文献
18.
5 alpha-Dihydrotestosterone (DHT) metabolism into 5 alpha-androstane-3 alpha, 17 beta-diol (alpha-diol) and 5 alpha-androstane-3 beta, 17 beta-diol (beta-diol) was studied in monolayer cultures of distinct cell populations from prepubertal male rats pituitaries. Cells were characterized through immunocytochemistry with the various antihormone antisera. Centrifugal elutriation was used to prepare a gonadotrope-enriched population "G" and a gonadotrope-depleted population "L", containing most lactotropes and somatotropes. Using centrifugation on Percoll gradient, two sub-populations, P1 and P2, were prepared by further fractionation of the "L" population. Cells were incubated for 48 h with [3H]DHT (1 microM, sp. act. 0.9 Ci/mmol) and metabolites extracted from the whole cell and medium. DHT was metabolized to about the same extent (30-40%) in all cell fractions. Compared with unfractionated population, the conversion of DHT into alpha-diol increased significantly in the P1 fraction, consisting of lactotropes, somatotropes and highly depleted in gonadotropes. This increase was lower in the somatotrope-enriched P2 fraction in which the amount of lactotropes was similar to P1 but that of gonadotropes slightly higher. In contrast, the conversion of DHT into alpha-diol decreased significantly in the "G" population compared with total or "L" fractions, whereas androstanedione formation, low in every population, increased significantly. The increase in alpha-diol formation could be related either to the decrease of gonadotropes or to a role of non-immunoreactive cells. As the beta-diol formation was constant in all cell types, the beta-diol/alpha-diol amount increased significantly in gonadotropes. Then, beta-diol and DHT could be both active steroids in gonadotrope regulation inasmuch as specific binding sites were identified for these two steroids. It can be concluded that DHT action at the pituitary level is subject to complex control mechanisms involving a specific balance of its metabolites in each particular cell type. 相似文献
19.
Moura G Vilarinho L Santos AC Machado J 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2000,125(3):293-306
Bivalve mollusks, such as the freshwater mussel Anodonta cygnea, show seasonal changes in calcification. This cycle of calcification must either be a cause or a consequence for seasonal fluctuations in the organic composition of the animal's fluids, haemolymph and extrapallial fluid, the liquid media for biomineralization. We monitored the fluids of A. cygnea, throughout a 1-year cycle, for the presence of organic constituents, known to be important for biomineralization, such as proteins, glycosaminoglycans (GAGs) and hexosamines. Proteins were subjected to further study, namely through the total amino acid determination and fraction separation by agarose gel electrophoresis. GAG levels were fairly constant throughout the year, with a maximum concentration in July and a minimum in January, a feature also detected for glucosamine, although with higher fluctuations. Proteins showed highly increased concentrations during June and July, both in total amounts and individual fractions. All fractions showed similar trends throughout the year, with lowest general levels in October, the starting month of a period when some fractions were not detectable at all. All fractions ended this low period in May, when a sometimes-important increase could be detected. As to the total amino acid composition of the fluids, the general trend followed that of proteins, except for ornithine (Orn), a non-proteic amino acid. The overall fluctuations detected in the biological fluids of A. cygnea suggest that the main variation related to the calcification cycle must be quantitative, since no different compounds appear in specific periods, to achieve also specific results. 相似文献
20.
Postnatal developmental patterns of uridine kinase were determined in crude subcellular fractions of the rat cerebellum, hypothalamus and cerebral cortex at ages 3 through 60 days. The highest specific activity and predominant distribution of enzyme was in the 105,000g supernatant of the 3 brain regions. Enzyme activity in hypothalamus and cerebral cortex was maximum at 3 days and decreased with age; in cerebellum it increased through 13 days and decreased thereafter. Thus, the pattern of activity in hypothalamus and cerebral cortex paralleled changes in DNA and RNA synthesis through age 60 days; in cerebellum, it more closely approximated changes in DNA synthesis during early development. Changes inK
m with aging suggest that the brain regions contain more than one form of enzyme. The highest particulate activity was in the microsomal fraction of the cerebellum and hypothalamus at all ages and in the cortex at 35 and 60 days. Relative specific activity for microsomal fractions of the brain regions at 60 days indicate a concentration of the enzyme which may be relevant in the maintenance of RNA activity in adult brain. 相似文献