Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00080 (Leaf)
 21,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bioflavonoids are potent inhibitors of lactate transport in Ehrlich ascites tumor cells. The most effective bioflavonoids have four to five hydroxyl groups. Sugar substitution at carbon three, or reduction of the double bond between carbons two and three, decreases their inhibitory activity. Quercetin, the most extensively studied of these compounds, inhibits lactate efflux by 50% at 0.1 micrograms/mg of protein. On addition of quercetin to glycolyzing Ehrlich ascites tumor cells, lactate accumulates inside the cell and the intracellular pH drops. Total lactate production is also inhibited. Nigericin prevents the internal acidification that occurs in the presence of quercetin and also reduces the inhibition of glycolysis. Thus, it appears that inhibition of lactate efflux can affect glycolysis through a lowering of the intracellular pH. The inhibitory effect of quercetin on glycolysis can be explained by its effect on lactate efflux and its previously reported effect on the Na+--K+ ATPase [Suolinna, E.--M., et al. (1974) J. Natl. Cancer Inst. 53, 1515].
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PMID:Inhibition of lactate transport and glycolysis in Ehrlich ascites tumor cells by bioflavonoids. 3 32

1) Denaturation of carp actomyosin during storage at -20 degrees was studied with particular interest in the cryoprotective effect of sodium glutamate, the most cryoprotective of the compounds tested previously. 2) Storage with glutamate prevented the rapid decrease in solubility, viscosity, and ATPase (EC 3.6.1.3)activity of actomyosin during storage. Ultracentrifugal studies suggested that aggregation occurred in the frozen state without glutamate, but that added glutamate prevented aggregation or denaturation. 3) Electron microscopy showed that the original actomyosin consisted of long filaments with typical "arrowhead" structures, and that these decomposed into small fragments and sticked with globular portions, forming loosely packed aggregates during storage without glutamate. On storage with glutamate, the filaments were well preserved, and their fine structure was clearer than that of the original sample. 4) Preparations of actomyosin extracted with 10 mM glutamate were of better quality and their ultrastructure and physicochemical and biochemical properties showed increased stability on freezing. 5) Freeze-denaturation seems to involve complicated aggregation with transconformation of proteins besides the side-to-side aggregation discussed previously.
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PMID:Prevention of freeze denaturation of carp actomyosin by sodium glutamate. 12 75

Purified (Na+, K+)-ATPase was studied by electron microscopy after thin sectioning, negative staining, and freeze-fracturing, particular emphasis being paid to the dimensions and frequencies of substructures in the membranes. Ultrathin sections show exclusively flat or cup-shaped membrane fragments which are triple-layered along much of their length and have diameters of 0.1-0.6 mum. Negative staining revealed a distinct substructure of particles with diameters between 30 and 50 A and with a frequency of 12,500 +/- 2,400 (SD) per mum(2). Comparisons with sizes of the protein components suggest that each surface particle contains as its major component one large catalytic chain with mol wt close to 100,000 and that two surface particles unite to form the unit of (Na+,K+)-ATPase which binds one molecule of ATP or ouabain. The further observations that the surface particles protrude from the membrane surface and are observed on both membrane surfaces in different patterns and degrees of clustering suggest that protein units span the membrane and are capable of lateral mobility. Freeze-fracturing shows intramembranous particles with diameters of 90-110 A and distributed on both concave and convex fracture faces with a frequency of 3,410 +/- 370 per mum(2) and 390 +/- 170 per mum(2), respectively. The larger diameters and three to fourfold smaller frequency of the intramembranous particles as compared to the surface particles seen after negative staining may reflect technical differences between methods, but it is more likely that the intramembranous particle is an oliogomer composed of two or even more of the protein units which form the surface particles.
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PMID:Ultrastructure of the sodium pump. Comparison of thin sectioning, negative staining, and freeze-fracture of purified, membrane-bound (Na+,K+)-ATPase. 14 37

The ultrastructure of Acinetobacter sp. strain HO1-N grown on hydrocarbon and nonhydrocarbon substrates was compared using thin sections and freeze-etching. Hydrocarbon-grown cells were characterized by the presence of intracytoplasmic membrane-bound hexadecane inclusions. This membrane did not exhibit a typical unit membrane structure but appeared as a monolayer. The freeze-etch technique revealed the internal structure of the hexadecane inclusions and provided evidence for the presence of a smooth-surfaced limiting membrane. Freeze-etching also revealed intracytoplasmic membranes in the hexadecane-grown cells. These ultrastructural modifications were not present in nonhydrocarbon-grown cells. The hexadecane inclusions were isolated from Acinetobacter. Negative-staining of the inclusions revealed electron-transparent vesicles approximating the size of the inclusions seen in whole cells. Freeze-etching of the purified inclusions revealed membrane-bound vesicles. The purified inclusions exhibited a relatively high value of lipid phosphorus to protein. The lipid composition and the electrophoretic banding pattern of the inclusions on sodium dodecyl sulfate-polyacrylamide gels were determined and compared with other membrane fractions (outer membrane and cytoplasmic membrane) previously isolated from this organism.
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PMID:Characterization of intracytoplasmic hydrocarbon inclusions from the hydrocarbon-oxidizing Acinetobacter species HO1-N. 17 78

1. UDP-glucose-sterol glucosyltransferase and nucleoside diphosphatases were isolated in a particulate fraction from 7-day-old etiolated pea seedlings. The glucosyltransferase and UDPase (uridine diphosphatase) are stimulated by Ca2+ cation, less so by Mg2+ cation, and inhibited by Zn2+. 2. Each activity has a pH optimum near 8. 3. The glucosyltransferase is specific for UDP-glucose as the glucosyl donor and is inhibited by UDP. Partial recovery from UDP inhibition is effected by preincubation of the enzyme. 4. Freeze-thaw treatment and subsequent sucrose-density-gradient centrifugation of the particulate fraction shows the glucosyltransferase to be widely distributed among cell fractions but to be most active in particles with a density of 1.15 g/ml. UDPase is most active in particulate material with a density of over 1.18 g/ml but an activity peak also appears at 1.15 g/ml. Of several nucleoside diphosphatase activities, UDPase activity is most enhanced by the freeze-thaw and sucrose-density-gradient-fractionation procedures. 5. Detergent treatment with 0.1% sodium deoxycholate allows the partial solubilization of the glucosyltransferase and UDPase. The two activities are similarly distributed between pellet and supernatant after high-speed centrifugation for two different time intervals. 6. A role for UDPase in the functioning of glucosylation reactions is discussed.
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PMID:Uridine diphosphate glucose-sterol glucosyltransferase and nucleoside diphosphatase activities in etiolated pea seedlings. 20 95

Groups of long Evans and CD-1 mice were immunized with vaccines prepared from epimastigotes of Trypanosoma cruzi, strains Y and Tulahuen, modified by various chemical means, or by the addition of immune sera. Freeze-thawed epimastigotes were used as a control antigen. Freeze-thawed epimastigotes, with and without saponin as adjuvant, gave significant protection against challenge with homologous trypomastigotes. Similar levels or protection were obtained in mice vaccinated with living epimastigotes. Treatment of epimastigotes by various chemical means, including sodium perchlorate failed to increase their immunogenicity, but did not reduce it. The addition of immune serum to the antigen may have slightly increased its immunogenicity.
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PMID:Immunization of mice against Trypanosoma cruzi: the effect of chemical treatment or immune serum on an epimastigote vaccine. 20 92

Toad bladder epithelial cells were isolated under mild conditions in a calcium-free medium; they were found to exclude trypan blue, to consume oxygen, and to respond to vasopressin with an increased rate of oxygen consumption. Since isolated toad bladder epithelial cells are mostly spherical in shape, the cell diameter can be accurately measured with an ocular micrometer of an inverted microscope. Epithelial cells swelled by 29+/-3% in the presence of KCN. This cyanide-induced swelling of cells was prevented by amiloride or, alternatively, by replacing NaCl by equiosmotic amounts of mannitol in the Ringer's fluid. Cells incubated in the presence of vasopressin swelled by 10+/-2%. Vasopressin and KCN acted synergistically in enhancing cell volume. Ouabain caused cells to swell by 9+/-2%, and this effect was not additive to the swelling seen with vasopressin. These observations are in accord with the theory of Leaf and his associates, that the predominant effect of vasopressin is to enhance sodium entry into the transporting epithelial cells of the toad urinary bladder.
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PMID:Action of vasopressin, ouabain, and cyanide on the volume of isolated toad bladder epithelial cells. 40 62

The effects of freeze-thawing of the tissue, and of protease inhibitors, on proteoglycans extracted sequentially from pig laryngeal cartilage with 0.15 M sodium acetate and 4 M guanidinium chloride were examined. Freeze-thawing of the tissue prior to extraction resulted in an increase in the proportion of smaller-sized proteoglycans in the sodium acetate extracts and a decrease in the proportion of aggregated proteoglycans in 4 M guanidinium extracts. In addition, a slight decrease in the hydrodynamic size of purified disaggregated proteoglycans was noted after freeze-thawing of the cartilage. When the protease inhibitors EDTA, 6-aminohexanoic acid and benzamidine hydrochloride were added to the sodium acetate buffer the yields of proteoglycans from fresh and freeze-thawed cartilage were diminished, but the inhibitors had no effect on the hydrodynamic size of the proteoglycans extracted with sodium acetate. Addition of the protease inhibitors to the 4 M guanidinium solvent increased the proportion of proteoglycans present in aggregates. The highest proportion of aggregated proteoglycans was obtained when fresh tissue was extracted in the presence of the inhibitors.
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PMID:Degradative enzymes of cartilage. Effects of freeze-thawing of the tissue prior to extraction, and of protease inhibitors, on proteoglycans extracted with iso-osmotic neutral salt and 4 M guanidinium chloride. 41 22

Pig kidney cells, LLC-PK1, grown by standard tissue-culture techniques form monolayers and maintain morphological features characteristic of epithelia. Cultures exposed to 2 X 10(-6) M [3H]ouabain for 30 min at 37 degrees C bound 7.77 +/- 0.37 pmol/mg protein. This could be reduced by 58% by incubation in the presence of 45 mM K+. Freeze-dry radioautographic localization of [3H]ouabain-binding sites revealed grains distributed only along that fraction of the plasmalemma directly facing the culture-dish surface. Binding and localization of [3H]ouabain were correlated with an inhibition of the Na+ pump in these cells because analysis of cellular electrolytes in control cultures versus those exposed to 10(-3) M ouabain revealed a fall in K+ from 419 +/- 9 to 173 +/- 4 mmol/kg dry wt with a reciprocal increase in Na+. There was no change in cell H2O. Similarly, oxygen consumption was reduced by 32% after exposure to ouabain. These results provide direct evidence that in epithelial cells in culture the membrane facing the culture dish corresponds to the basolateral membrane of epithelial cells in vivo.
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PMID:Localization of [3H]ouabain-sensitive Na+ pump sites in cultured pig kidney cells. 42 47

Oligomers of hyaluronic acid were prepared by digestion of hyaluronic acid from rooster combs with testicular hyaluronidase (hyaluronate 4-glycanohydrolase, EC 3.2.1.35), leech head hyaluronidase (hyaluronate 3-glycanohydrolase, EC 3.2.1.36), and with fungal hyaluronidase (hyaluronate lyase from Streptomyces hyalurolyticus). The oligomers were fractionated by gel permeation, using Sephadex G-50. Oligomers isolated after incubation of the hyaluronic acid with the testicular hyaluronidase were further modified. To prepare oligomers with N-acetylglucosamine at both ends, terminal nonreducing glucuronic acid residues were removed with beta-glucuronidase. Reducing terminal N-acetylglucosamine residues were removed by reaction under mildly alkaline conditions. The reducing terminal N-acetylglucosamine residues were also reduced with sodium borohydride to form N-acetylglucosaminitol. The potentials of the various oligosaccharides to bind to the proteoglycan from bovine nasal septum cartilage were estimated by determining their effectiveness as inhibitors of the proteoglycan-hyaluronate interaction. The present study shows that, to bind maximally to the proteoglycan, the hyaluronate oligosaccharide must be at least 10 sugar residues in length and be terminated at the nonreducing and reducing ends with a glucuronate residue and an N-acetylglucosamine residue, respectively. Sugar residues extended beyond this basic decasaccharide, do not interact with the hyaluronate binding site on the proteoglycan.
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PMID:Interactions of cartilage proteoglycans with hyaluronate. Inhibition of the interaction by modified oligomers of hyaluronate. 43 8


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