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1.
The molecular weight of the precursor polyprotein to the envelope proteins of Rauscher murine leukemia virus is reduced from 85,000 to 68,000 daltons when synthesized in the presence of tunicamycin, a specific inhibitor of the synthesis of oligosaccharides that attach to glycoproteins via asparagine residues. The unglycosylated precursor protein (Pr68) is synthesized at a rate comparable to that of the normal carbohydrate-containing envelope precursor (gPr85). Pr68 is not proteolytically processed and remains undegraded in the cell. Thus, most if not all of the carbohydrate content of gPr85 is N-linked, and glycosylation appears to be necessary for normal processing of precursor proteins into viral particles. 相似文献
2.
cultures were starved, deciliated and incubated in a reciliation medium in the presence and absence of tunicamycin. This antibiotic was shown to have no effect on the rate of reciliation or the appearance of the organisms even when present in relatively large amounts, although cell division was blocked. A small inhibition of protein synthesis was noted in the presence of tunicamycin, but mannose incorporation was totally abolished. It was concluded that the reciliation of these organisms takes place by a mechanism that does not require the synthesis of glycoprotein. 相似文献
3.
4.
T. Sasaki M. Yamasaki B. Maruo Y. Yoneda K. Yamane A. Takatsuki G. Tamura 《Biochemical and biophysical research communications》1976,70(1):125-131
Several tunicamycin resistant mutants were obtained from NA64. One of them, B7 strain produced a 5-fold larger amount of α-amylase than NA64 did. Only the amount of α-amylase, among excreted proteins, was enhanced. Genetic analyses by transformation suggested that a single mutation in B7 induced both resistance to tunicamycin and hyperproductivity of extracellular α-amylase. 相似文献
5.
Electron spin resonance detection of free radicals in the mercaptan-activation and UV-inactivation of neocarzinostatin 总被引:3,自引:0,他引:3
Differentiation of chick embryo myoblasts requires both cell-cell recognition and cell-cell fusion. Prostaglandin E1 is known to play a role in controlling fusion, and a specific receptor has been postulated. We demonstrate two peaks of specific binding activity for prostaglandin E1 during myoblast differentiation : one at 36 hours and one at 44 hours of culture. The prostaglandin binding activity of both peaks is sensitive to the inhibitors of prostaglandin synthesis, indomethacin and aspirin, and to the antibiotic tunicamycin. The 36 hour peak of binding activity occurs at the same time as the process of cell-cell recognition (24–36 hours) and recognition and prostaglandin binding exhibit similar sensitivity to indomethacin, aspirin and tunicamycin. 相似文献
6.
Mary Ann Dombrink-Kurtzman William E. Dick Kermit A. Burton Martin C. Cadmus Morey E. Slodki 《Biochemical and biophysical research communications》1983,111(3):798-803
Evidence is presented for the presence of a new lectin activity in soybean seeds [ (L.) Merrill] that has specificity towards the 4-O-methyl--glucurono--rhamnan exopolysaccharide produced by certain strains of . Bacterial agglutination and precipitin reactions revealed the lectin activity in phosphate-buffered saline extracts of seeds of all cultivars tested, including the “lectinless” varieties. Reaction of such extracts with carbohydrate haptens demonstrated that the specificity of the binding was towards 4--methyl--glucuronic acid, -glucuronic acid and their methyl glycosides. 相似文献
7.
W.M. Glöckner R.A. Newman G. Yhlenbruck 《Biochemical and biophysical research communications》1975,66(2):701-705
The carbohydrate moiety of the “antifreeze” glycoprotein from was found to be β-D-galactosyl 1–3 N-acetyl galactosamine by gasliquid chromatography. The glycoprotein inhibited anti-T antibody from human serum and lectin, but was inactive against . Native “antifreeze” glycoprotein did not inhibit the agglutinins from or , although after Smith degradation showed a strong inhibition towards them. Inhibition of the latter agglutinin demonstrates the carbohydrate-protein linkage to be α-linked. The presence of the Thomsen-Friedenreich antigen (T-antigen) on the “antifreeze” glycoprotein and its relation to tumour cell surfaces is briefly discussed. 相似文献
8.
Phenylacetic, 3-phenylpropionic, -hydroxyphenylacetic and 3 (-hydroxyphenyl) propionic acids together with the series of C2 to C6 saturated fatty acids previously reported in the anal sac secretion of the red fox () are identified as constituents of the anal sac secretion of the lion (Panthera leo). All these compounds are also observed in the anal sac secretion of the red fox using gas chromatography. The aerobic microflora of red fox and domestic dog () anal sac secretion samples invariably consisted predominantly of and . The hypothesis that the secretion volatiles so far identified may be microbiologically produced is examined. 相似文献
9.
Robert J. Bjercke Peggy M. Hale Wayne D. Mercer William L. McGuire 《Biochemical and biophysical research communications》1981,99(2):550-556
Fusion of cells of the NS-1 mouse myeloma line with spleen cells from mice immunized against ovalbumin produced hybrid cells which continuously secrete antibodies specific for ovalbumin. One of these cells was used to establish a cloned line. Studies of its antibody obtained either from ascites fluid or from medium from hybridoma cultures showed high titer and specificity against ovalbumin using the double antibody technique with rabbit anti-mouse immunobeads; the antibody proved to be of the IgG1 (kappa) subclass and type. 相似文献
10.
Kenji Kohno Akiyoshi Hiragun Akira Takatsuki Gakuzo Tamura Hiromi Mitsui 《Biochemical and biophysical research communications》1980,93(3):842-849
ST 13 cells are a clonal line of murine fibroblasts that are capable of differentiating into adipocyte-like cells . When the cells were maintained as a confluent monolayer, they began to accumulate lipid droplets and to exhibit a rapid increase of insulin binding activity. Tunicamycin, a specific inhibitor of dolichol-mediated protein glycosylation, blocked this adipose conversion without affecting cell growth and total protein synthesis. The inhibitory effect of tunicamycin was dose-dependent and reversible. Enhancement of the incorporation of [14C]acetate into triglyceride fraction accompanying the adipose conversion was completely inhibited by tunicamycin, whereas the incorporation into phospholipid fraction was only partially affected. The insulin binding activity increased about 10-fold during differentiation, but was completely suppressed in tunicamycin-treated cells. 相似文献
11.
S H de Bruin H S Rollema L H Janssen G A van Os 《Biochemical and biophysical research communications》1974,58(1):210-215
The immobilization of glucose oxidase, a glycoenzyme from consisting of 16% carbohydrate, has been achieved by oxidizing its carbohydrate residues with periodic acid followed by coupling the activated enzyme to water-insoluble -aminostyrene. At pH 5.6 and 25°, approximately 60% of the carbohydrate residues are oxidized, but the enzyme retains full activity. No oxidation of any amino acid residue is evident. The enzyme-polymer conjugate derived from this activated enzyme retains full activity and even shows a slightly enhanced thermal stability at 60° compared with the soluble native and oxidized glucose oxidases. 相似文献
12.
Natalia Grinberg Takhir Bikbov Valeri Grinberg Tatiana Chaika Iosif Vaintraub Vladimir Tolstoguzov 《International journal of biological macromolecules》1985,7(3):152-160
Studies were made on the boundary conditions for thermotropic ovalbumin gelation at pH within the range 2.5 to 10.0. The pH dependence of the gelation threshold, C0, and denaturation temperature, Td, were obtained. The dependence C0(pH) has a sharp minimum close to the isoelectric point (pl). Over pH range 2.5 to 4.0 the dependence Td(pH) is linear; although above pI it shows unusual behaviour. Td increases smoothly, becoming a constant value (Td=80°C) at pH 7. Analysis of the temperature dependence of Leu's line integral intensity in the p.m.r. spectrum of ovalbumin shows that the temperature threshold of thermotropic gelation closely approximates to Td. A diagram for the state of an ovalbumin -water system was constructed in temperature-concentration-pH coordinates. The dependences of the initial shear modulus for thermotropic ovalbumin gels on the concentration (0.06≤C≤0.25g/cm3 were obtained at pH 4.0, 7.0, 8.5, 10.0. They are equivalent to the concentration dependence of the equilibrium elastic modulus Ee(C). The dependences obtained may be reduced to the theoretical master dependence of Hermans, , where is the reduced concentration. Hermans' theory, based o the model for random cross-linking of linear identical macromolecules without cyclization, adequately describes the equilibrium elastic properties of thermotropic ovalbumin gels. 相似文献
13.
P.A. Murray M.J. Levine L.A. Tabak M.S. Reddy 《Biochemical and biophysical research communications》1982,106(2):390-396
Evidence is presented for the presence of a lectin on with specificity towards the major acidic oligosaccharide of human salivary mucin. Based upon hemagglutination inhibition studies, the strongest inhibitor was NeuAcα2,3Galβ1,3GalNAcol ? NeuAcα2,3Galβ1,4Glc ? NeuAc > Gal. Interactions were not heat sensitive or charge dependent, and were not affected by the presence of bacterial cell associated neuraminidase. The lectin could be extracted from with lithium 3,5-diiodosalicylate (LIS). Incubation of LIS extracts with carbohydrate ligands demonstrated that the specificity of binding was . 相似文献
14.
Human erythrocyte membranes were solubilized in 5% Triton X-100 and the acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) was isolated by affinity chromatography utilizing a specific inhibitor, ammonium chloride, bound to Sepharose 4B. After a repeated chromatography acetylcholinesterase was found to be homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Immunization of rabbits with acetylcholinesterase elicited the formation of an antiserum which gave single precipitin lines with the enzyme on immunodiffusion and rocket, crossed and immuno-electrophoreses. The purified enzyme had a specific activity of 418 units/mg protein. The value of acetylcholinesterase with acetylthiocholine as substrate was . Isoelectric focusing of acetylcholinesterase in the presence of Triton X-100 and within the pH ranges of 3–10 and 3–6 exhibited a single peak of enzyme activity with a of 4.8. The results of amino acid and carbohydrate analyses showed that acetylcholinesterase is a glycoprotein with a carbohydrate/protein weight ratio of 0.16 and glucose, galactose, mannose, glucosamine, galactosamine and sialic acid as the sugar components. The N-terminal amino acid was blocked. Lipid, phosphorus and fatty acid analyses indicated phosphatidylserine and cholesterol as the major lipid components of acetylcholinesterase. The apparent subunit molecular weight estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis in the absence of 2-mercaptoethanol was 160 000 and in its presence, 80 000. The kinetic studies showed a competitive inhibition of acetylcholinesterase by its antibodies. Agglutination of human red cells by monospecific antiserum to acetylcholinesterase confirmed that the antigenic site(s) of the enzyme is localized on the outer surface of the erythrocyte membrane. 相似文献
15.
Anthony L. Tarentino Frank Maley 《Biochemical and biophysical research communications》1975,67(1):455-462
The substrate specificities of the endo-β-N-acetylglucosaminidases from and were compared and found to differ considerably. The enzyme from released Asn-GlcNAc-Fuc-containing glycopeptides from exoglycosidase-treated acidic IgM glycopeptides but was limited in its capacity to hydrolyze ovalbumin glycopeptides larger than Asn(GlcNAc)2(Man)5. In contrast, the enzyme from hydrolyzed this and larger neutral oligosaccharides but could not hydrolyze the above fucose-containing IgM glycopeptides. Removal of the fucose residue, however, converted the latter to an active substrate for the enzyme, thus broadening its substrate range to encompass most of those substrates hydrolyzed by the endoglycosidase. 相似文献
16.
Recent work (Hizi and Yagil [1974] Eur. J. Biochem. : 211–221, and Kelly [1975] Fed. Proc. : 881) suggests that the marked increase in rat liver glucose-6-phosphate dehydrogenase activity which is observed upon feeding an animal a high carbohydrate diet does not involve an increase in the total amount of enzyme present. In contrast, the data presented herein involving immunological titrations of rat liver glucose-6-phosphate dehydrogenase indicates that the increase in enzyme activity resulting from feeding a high carbohydrate diet does involve an increase in the total amount of enzyme present. 相似文献
17.
Phenol extraction of bovine milk fat globule membrane gave a glycoprotein fraction which, in sodium dodecyl sulphate electrophoresis, showed three major bands, all staining for both protein and carbohydrate. Alkaline borohydride treatment and desialylation of the glycoprotein fraction released the reduced disaccharide β-d-galactosyl(1 → 3)- (T-antigen), which was identified by gas chromatography using a standard. All of the disaccharide units in the native glycoprotein were shown to be substituted by sialic acid, and a tetrasaccharide containing the disaccharide plus two molecules of sialic acid was isolated following alkaline borohydride treatment of the glycoprotein and gel filtration. Periodate oxidation of native and desialylated glycoprotein, together with paper chromatography of alkali degraded oligosaccharide fragments, indicated that the major alkali-labile oligosaccharide of the glycoprotein fraction is a tetrasaccharide containing substituted by sialic acid at position C3 of the galactosyl and position C6 of the residue. Evidence was also obtained for the presence of small amounts of unsubstituted alkali-labile linked directly to protein in the native glycoprotein.Serological evidence using agglutinins from Vicia graminea, Arachis hypogoea and human anti-T serum confirmed the presence in the native glycoprotein of a sialic acid substituted T-antigen. Similar evidence using agglutinins from Helix pomatia and Cepaea hortensis also confirmed the presence of terminal alkali-labile in the native glycoprotein. 相似文献
18.
Influence of 2-deoxy-D-glucose on galactofuranosidase and peptidophosphogalactomannan synthesis in Penicillium charlesii 总被引:1,自引:0,他引:1
2-deoxy-D-glucose inhibits synthesis of the glyco-enzyme -β-D-galactofuranosidase and its secretion into the growth medium of cultures. In contrast, the synthesis of peptidophosphogalactomannan, an extracellular glycopeptide (peptido-polysaccharide) occurs in nearly normal quantities in the presence of 2-deoxy-D-glucose. The peptidophosphogalactomannan's composition in cultures containing 2-deoxy-D-glucose was comparable to that obtained from cultures containing no added 2-deoxy-D-glucose. We conclude peptidophosphogalactomannan is not derived from mural or extracellular glycoprotein(s) whose synthesis is inhibited by 2-deoxy-D-glucose. 相似文献
19.
The rate of fluid secretion in vitro by Malpighian tubules of 3-day-old adult blowflies (Calliphora vicina) is increased by more than 8 times when exposed to an extract of the fly's thoracic ganglion and abdominal nerves. Smaller amounts of stimulatory activity are also retrievable from other body tissues: some activity is present in the brain, but other tissue activity is consistent with the presence of the stimulatory factor in fine branches of the abdominal nerves. It is suggested that this factor is a diuretic hormone.Maximal stimulation of fluid secretion is achieved within 2–3 min of exposure to the hormone, but the rate of secretion decays only slowly when the hormone is removed ().The hormone is stable to boiling and freezing, and enzyme experiments suggest it is a polypeptide.The hormone is inactivated when incubated in the presence of haemolymph, but the Malpighian tubules themselves do not appear to break down or excrete the hormone. 相似文献
20.
R. Aschaffenburg C.C.F. Blake J.M. Burridge M.P. Esnouf 《Journal of molecular biology》1977,114(4):575-579
Crystals of fragment 1 of bovine prothrombin grown from phosphate at pH 7.5 are tetragonal, space group P41222 or P43212 with , with probably one molecule of 22,000 molecular weight in the asymmetric unit. The presence of 17.5% carbohydrate in the fragment may account for the high liquid content (60%) of the crystals. 相似文献