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Showing papers on "Affinity chromatography published in 1980"


Journal ArticleDOI
TL;DR: Epidermal growth factor-enhanced protein kinase activity in plasma membrane preparations of A-431 human epidermoid carcinoma cells was shown to involve the phosphorylation of tyrosine residues, which was detected in both endogenous membrane proteins and in histone when added as an exogenous protein substrate.

1,096 citations


Journal ArticleDOI
TL;DR: Analysis of the affinity-purified preparation by sodium dodecyl sulfate-gel electrophoresis indicates the presence of one major protein band of molecular weight 150,000 which is the receptor for EGF and is a substrate of the phosphorylation reaction.

783 citations


Journal ArticleDOI
TL;DR: These monoclonal antibodies should prove useful in the study of estrogen receptors of human reproductive tissues, in particular for the radioimmunochemical assay and immunocytochemical localization of receptors in breast cancers.
Abstract: Extranuclear estrogen receptor protein (estrophilin) of MCF-7 human breast cancer cells was purified by passage of the cytosol fraction of a cell homogenate through an affinity column of estradiol linked to Sepharose by a substituted di-n-propyl sulfide bridge in the 17 alpha position. Elution with 50 micro M [3H]estradiol in 10% (vol/vol) dimethyl formamide/0.5 M sodium thiocyanate gave 40% recovery of [3H]estradiol-estrophilin showing 14% of the specific radioactivity expected for the pure complex. Serum from a Lewis rat immunized with this partially purified estradiol-receptor complex contained antiestrophilin antibodies that reacted not only with nuclear and extranuclear estradiol-receptor complexes from MCF-7 cells but also with estrophilin from rat, calf, and monkey uterus, hen oviduct, and human breast cancers. Splenic lymphocytes from the immunized rat were fused with cells of two different mouse myeloma lines (P3-X63-Ag8 and Sp2/0-Ag14) to yield hybridoma cultures, 2% of which produced antibodies to estrophilin. After cloning by limiting dilution, three hybridoma lines secreting antiestrophilin were expanded in suspension culture and as ascites tumors in athymic mice to provide substantial quantities of monoclonal antibodies that recognize mammalian but not avian estrophilin and that show different degrees of reactivity with receptor from nonprimate sources. By growing the clone from Sp2/0 in the presence of [35S]methionine, radiolabeled monoclonal IgG has been prepared. These monoclonal antibodies should prove useful in the study of estrogen receptors of human reproductive tissues, in particular for the radioimmunochemical assay and immunocytochemical localization of receptors in breast cancers.

534 citations


Journal ArticleDOI
TL;DR: Subfractionation of HDL by heparin-Sepharose affinity column chromatography provides an attractive alternative to methods based solely on ultracentrifugation, in that it subfractionates HDL into subclasses with differing apoprotein contents that impart distinct metabolic characteristics to each class.

325 citations


Journal ArticleDOI
TL;DR: Extracellular laccase (EC 1.18.1) of the cultivated mushroom Agaricus bisporus was produced constitutively in defined or complex media and the substrate specificity was similar to that of other fungal laccases.
Abstract: SUMMARY: Extracellular laccase (EC 1.14.18.1) of the cultivated mushroom Agaricus bisporus was produced constitutively in defined or complex media. No enzyme induction was found after treatment with cycloheximide or with other potential inducers such as toluidine or xylidine. The enzyme was purified to homogeneity by ammonium sulphate precipitation, ion-exchange chromatography, gel filtration and affinity chromatography. It eluted as a single peak from ion-exchange, gel filtration and affinity columns and sedimented as a single band on centrifugation. It showed four enzymically active bands on electrophoresis and a diffuse band on isoelectric focusing. Its molecular weight was estimated to be about 100000 and the enzyme contained 15% carbohydrate and two atoms of copper per molecule. The substrate specificity was similar to that of other fungal laccases. Antiserum prepared against the purified enzyme gave one major precipitin band.

195 citations


Journal ArticleDOI
TL;DR: It is demonstrated that thrombasthenic homozygotes lack and heterozygotes have a partial deficiency of this complex, and made possible the isolation of this membrane protein which may be required for normal platelet aggregation and clot retraction.
Abstract: We used the hybridoma technique to characterize further the platelet glycoprotein abnormality in Glanzmann's thrombasthenia. Spleen cells from Balb/c mice immunized with human platelets were fused to mouse myeloma cell line Sp2/0-Ag14. Hybridoma lines producing a variety of antiplatelet antibodies were isolated by hypoxanthine-aminopterin-thymidine selection and cloned, and purified monoclonal IgG from six lines was prepared. One of these lines, 8aB5-9, produced an antibody, Tab, that binds to a protein on normal but not thrombasthenic platelets. We isolated this protein from Triton X-100 solubilized normal platelet membranes by affinity chromatography on Tab-Sepharose. As determined by SDS polyacrylamide gel electrophoresis, the isolated protein is a complex of glycoproteins IIb and IIIa, because the two subunits comigrate with glycoproteins IIb and IIIa of whole platelets and show identical changes in mobility after disulfide bond reduction. We prepared (125)I-Tab to determine the number of glycoprotein IIb-IIIa complexes on normal and thrombasthenic platelets by a direct binding assay. Platelets from 17 normal donors bound 39,000+/-4,600 (SD) Tab molecules/platelet. Platelets from four patients with thrombasthenia lacked Tab binding sites (<5%). Five obligate and four presumed heterozygotes for thrombasthenia bound 24,500+/-5,800 Tab molecules/platelet. The platelet alloantigen, Pl(Al), is not that recognized by Tab, because platelets from three Pl(Al)-negative subjects bound Tab normally. Studies with the Tab antibody have (a) enabled quantitation of the number of glycoprotein IIb-IIIa complexes on normal platelet membranes, (b) demonstrated that thrombasthenic homozygotes lack and heterozygotes have a partial deficiency of this complex, and (c) made possible the isolation of this membrane protein which may be required for normal platelet aggregation and clot retraction.

192 citations


Journal ArticleDOI
TL;DR: Rin-monoclonal antibody hybrids of this type combine a high degree of cell-type selectivity and toxicity and may have pharmacologic utility as antitumor reagents.
Abstract: The cell-type specificity of the toxin ricin, which ordinarily binds, enters, and kills cells through receptors containing galactose, has been altered by covalently binding it to a monoclonal antibody and by reversibly binding it to lactose. The antibody, a monoclonal rat IgG2b directed against the Thy 1.2 antigen, provides ricin with a new binding site for the murine thymus cell surface. Addition of lactose saturates the galactose-binding site on ricin and inhibits ricin from binding and killing cells via the galactose-containing receptors. The antibody-ricin hybrid protein, anti-Thy 1.2-ricin, formed with a thioether linkage, has been purified by size exclusion and affinity chromatography. When assayed by inhibition of protein synthesis of EL-4 cells, which express the Thy 1.2 antigen anti-Thy 1.2-ricin is equally as toxic as ricin on a molar basis. The hybrid protein toxicity is unchanged in the presence of 100 mM lactose, whereas unmodified ricin toxicity is reduced to 1% of its toxicity in the absence of lactose. This demonstrates the altered receptor specificity of the ricin hybrid. The cell-type specificity of the anti-Thy 1.2-ricin inhibition of protein synthesis correlates with the presence of the Thy 1.2 antigen. Anti-Thy 1.2-ricin at 4 microgram/ml in the presence of lactose inhibits protein synthesis within 3.5 hr by 60-80% in EL-4 cells but does not affect Thy 1.1 alloantigen and HeLa cells that lack the Thy 1 antigen. Anti-Thy 1.2-ricin in the presence of lactose selectively kills EL-4 cells at concentrations that do not kill AKR-K36 cells. This selectivity, expressed as the ratio of anti-Thy 1.2-ricin concentrations required to kill 40% of both cell types, is 700. Ricin-monoclonal antibody hybrids of this type combine a high degree of cell-type selectivity and toxicity and may have pharmacologic utility as antitumor reagents.

189 citations


Journal ArticleDOI
TL;DR: Findings together with the results of hemagglutination and precipitation studies indicate that the lectin combines the terminal fucose in the carbohydrate chain but does not require a particular linkage to the penultimate sugar moiety.
Abstract: A fucose-binding lectin from fruiting bodies of Aleuria aurantia was purified by affinity chromatography by using the H-active glycopeptide of desialyzed porcine submaxillary mucine coupled to Sepharose 4B and eluting with L-fucose. Homogeneity of the active protein was confirmed by polyacrylamide gel electrophoresis, isoelectric focusing, column chromatography using Sephadex G-100, and ultracentrifugal analyses. It has a molecular weight of 72 000 and is proposed to be a dimer of identical subunits, each of which has combining site of uniform affinity. Chemical analyses revealed the absence of the sulfur-containing amino acid and carbohydrate, neutral and amino sugar, in the lectin molecule. It agglutinated human erythrocytes of all ABO and Lewis types, Bombay phenotype, and group O cells treated with alpha (1 leads to 2)-fucosidase. In double-diffusion experiments, the lectin formed a single precipitin line which fused with all of the fucose-containing blood-group substances tested, including the alpha-fucosidase-treated materials. These findings together with the results of hemagglutination and precipitation studies indicate that the lectin combines the terminal fucose in the carbohydrate chain but doses not require a particular linkage to the penultimate sugar moiety.

189 citations


Journal ArticleDOI
01 Feb 1980-Science
TL;DR: The purification of human fibroblast interferon has been simplified to a two-step procedure consisting of affinity chromatography on Blue Sepharose and sodium dodecyl sulfate polyacrlamide gel electrophoresis.
Abstract: The purification of human fibroblast interferon has been simplified to a two-step procedure consisting of affinity chromatography on Blue Sepharose and sodium dodecyl sulfate polyacrlamide gel electrophoresis. A preliminary amino acid composition and the sequence of the 13 amino-terminal residues of homogeneous interferon prepared by this method is reported.

175 citations


Journal ArticleDOI
TL;DR: It is demonstrated that only one of the two toxin binding sites on the receptor monomer, the one which can be affinity alkylated with 4-(N-maleimido)benzyltrimethylammonium, controls the carbamylcholine-induced opening of the cation channel.

172 citations


Journal ArticleDOI
TL;DR: A rapid methof for preparation of membrane fractions highly enriched in nicotinic acetylcholine receptor from Torpedo californica electroplax is described, which yields solubilized receptor preparations comparable with the most highly purified protein obtained by affinity-chromatographic procedures.
Abstract: A rapid methof for preparation of membrane fractions highly enriched in nicotinic acetylcholine receptor from Torpedo californica electroplax is described. The major step in this purification involves sucrose-density-gradient centrifugation in a reorienting rotor. Further purification of these membranes can be achieved by selective extraction of proteins by use of alkaline pH or by treatment with solutions of lithium di-idosalicylate. The alkali-treated membranes retain functional characteristics of the untreated membranes and in addition contain essentially only the four polypeptides (mol.wts. 40000, 50000, 60000 and 65000) characteristic of the receptor purified by affinity chromatography. Dissolution of the purified membranes or of the alkali-treated purified membranes in sodium cholate solution followed by sucrose-density-gradient centrifugation in the same detergent solution yields solubilized receptor preparations comparable with the most highly purified protein obtained by affinity-chromatographic procedures.

Journal ArticleDOI
TL;DR: The second hypothesis stated above was proven to be correct for D-alanine carboxypeptidase, and several new methods were developed in the course of this work, including a rapid penicillin-binding assay, use of hydroxylamine to protect peptides against carbamylation during ion exchange chromatography in concentrated urea solutions, and 3) gel filtration Chromatography in 70% formic acid, a universal solvent for peptides.

Journal ArticleDOI
TL;DR: β2-G-I in rats is also present in all serum lipoprotein density classes and was found in VLDL, and strongly binds to heparin and Intralipid®.

Journal ArticleDOI
TL;DR: Endogenous lactose-binding proteins from adult chicken liver and intestine have been purified to homogeneity by affinity chromatography on asialofetuinderivatized Sepharose, followed by isoelectric focusing, and the lectin from adult liver appears identical with the lect in previously purified from embryonic skeletal muscle.

Journal Article
TL;DR: It is demonstrated that gallium at the tracer level in blood is exclusively bound to and transported by transferrin, and indicates that electrophoresis and dialysis of easily dissociable metal complexes are subject to significant artifacts.
Abstract: As a crucial step toward the understanding of the tumor localization of gallium, we have re-investigated its binding and transport in blood. The studies were performed in vivo by injection of gallium-67 citrate in rabbits, and in vitro by incubation of gallium-67 citrate with individual plasma proteins. By ultrafiltration and gel filtration chromatography, rabbit plasma samples showed essentially complete protein binding, whereas dialysis indicated considerable nonprotein-bound gallium, the amount depending on the dialysis medium. According to electrophoresis, total binding was inversely proportional to electrophoresis time. Affinity chromatography showed all gallium to be bound to transferrin, whereas electrophoresis caused continuous dissociation of gallium from transferrin, with the resulting unbound radioactivity appearing in various other protein bands. Similarly, the binding of gallium to transferrin in the in vitro incubation studies was inversely proportional to electrophoresis time, whereas ultrafiltration and gel filtration chromatography showed all gallium to be transferrin-bound. No binding of gallium to other proteins, such as albumin, was observed. This study demonstrates that gallium at the tracer level in blood is exclusively bound to and transported by transferrin, and indicates that electrophoresis and dialysis of easily dissociable metal complexes are subject to significant artifacts. Accurate determination of protein binding of radiopharmaceuticalsmore » requires a combination of analytical techniques and cautious interpretation of the results.« less

Journal ArticleDOI
TL;DR: The high affinity of this LPM protein for organic anions suggests that it may function as a hepatocellular organic anion receptor, and its role in transport of these compounds is unknown.
Abstract: Uptake of bilirubin, sulfobromophthalein (BSP), and other organic anions by the liver is a process with kinetics consistent with carrier mediation. The molecular basis of this transport mechanism is unknown. In the search for the putative organic anion carrier or receptor, the interaction of BSP with rat liver cell plasma membrane (LPM) has been studied. Specific binding of [(35)S]BSP to LPM was determined using a filtration assay. Results revealed high affinity (K(a) = 0.27 muM(-1)), saturable (6.3 nmol/mg protein) binding, which was eliminated after preincubation with trypsin. Although [(35)S]BSP was strongly bound to LPM, the binding was rapidly reversible, preventing direct identification and study of a specific binding site(s). To avoid this problem, a photoaffinity probe was devised, in which [(35)S]BSP is covalently bound to LPM after exposure to ultraviolet light. Subsequent sodium dodecyl sulfate gel electrophoresis and fluorography revealed radioactivity predominantly associated with a single 55,000-mol wt protein. A protein with identical electrophoretic mobility was purified from deoxycholate solubilized LPM after affinity chromatography on glutathione-BSP-agarose gel. This protein migrated as a single band on sodium dodecyl sulfate gel electrophoresis and on urea gel isoelectric focusing. It contained 1-2 residues of sialic acid per 55,000-dalton protein, and was immunologically distinct from rat albumin and ligandin. It bound bilirubin with a K(d) of 20 muM, as determined by tryptophan fluorescence quenching. Although the high affinity of this LPM protein for organic anions suggests that it may function as a hepatocellular organic anion receptor, its role in transport of these compounds is unknown.

Journal ArticleDOI
TL;DR: High-Performance Liquid Affinity Chromatography of Nucleosides, Nucleotides and Carbonhydrates with Boronic Acid-Substituted Microparticulate Silica for high-performance liquid chromatography of nucleosides and carbonhydrates.

Journal ArticleDOI
TL;DR: A number of biomolecules were coupled covalently by nucleophilic displacement to agarose preparations substituted with tosyl groups to demonstrate the immobilization of proteins.
Abstract: A number of biomolecules were coupled covalently by nucleophilic displacement to agarose preparations substituted with tosyl groups. In one series of experiments N6-(6-aminohexyl)-adenosine 5′-monophosphate and N6-(6-aminohexyl)adenosine 2′,5′-bisphosphatewere bound by their terminal amino groups to the polysaccharide support. It could be shown that from a mixture of lactate and 6-phosphogluconate dehydrogenase the immobilized monophosphate showed bio-affinity only for NAD+-dependent lactate dehydrogenase, whereas the immobilized bisphosphate showed affinity only for the NADP+-dependent 6-phosphogluconate dehydrogenase. Furthermore, the immobilized monophosphate (5 μmol/g wet gel) was applied for the single-step purification of lactate dehydrogenase from crude beef heart extract. To demonstrate the immobilization of proteins, soybean trypsin inhibitor (75 mg/g dry support) was immobilized to tosylated agarose, tested as affinity chromatography material and shown to bind 60 mg trypsin/g dry gel. Horseradish peroxidase and horse liver alcohol dehydrogenase were used as model enzymes. Although no optimization had been attempted, the former (approximately 70 mg/g dry support) had a coupling yield of approximately 18% with a specific activity (relative to soluble enzyme) of approximately 10%, whereas approximately 60% of alcohol dehydrogenase was coupled (approximately 100 mg/g dry support) with a specific activity of approximately 25%.

Journal ArticleDOI
TL;DR: The efficient direct binding of fibronectin to actin suggests that interactions between these proteins might also take place in vivo but further studies are needed to elucidate the biological significance of this affinity.
Abstract: Affinity chromatography with actin-Sepharose conjugates of purified human fibronectin, normal human plasma, or serum-free culture fluid from human fibroblasts showed that fibronectin molecules can directly bind to actin. A quantitative recovery of soluble human fibronectin was accomplished by chromatography on actin immobilized on Sepharose beads. Human fibronectin molecules bound to actin-Sepharose were eluted with 0.25--0.35 M potassium bromide, and these molecules competed in a species-specific radioimmunoassay for human fibronectin. The subunits of fibronectin isolated by actin-Sepharose chromatography comigrated in SDS polyacrylamide gel electrophoresis with those of electrophoretically homogeneous fibronectin purified by conventional procedures. The efficient direct binding of fibronectin to actin suggests that interactions between these proteins might also take place in vivo but further studies are needed to elucidate the biological significance of this affinity.

Journal ArticleDOI
TL;DR: An asparagine-linked oligosaccharide with an unusual structure has been isolated from Pronase digests of Chinese hamster ovary cell glycoproteins using gel filtration, ion exchange chromatography, and affinity chromatography on lectin-Sepharose columns.

Journal ArticleDOI
TL;DR: The proteins seem to act catalytically, since they inactivate a molar excess of ribosomes in the lysate system, and are somewhat toxic to mice.
Abstract: 1. A haemagglutinating lectin was purified from the seeds of Momordica charantia by affinity chromatography on Sepharose 4B and on acid-treated Sepharose 6B. It has mol.wt. 115 000 and consists of four subunits, of mol.wts. 30 500, 29 000, 28 500 and 27 000. 2. The lectin inhibits protein synthesis by a rabbit reticulocyte lysate with an ID50 (concentration giving 50% inhibition) of approx. 5 micrograms/ml. Protein synthesis by Yoshida ascites cells is partially inhibited by the lectin at a concentration of 100 micrograms/ml. 3. From the same seeds another protein was purified which has mol.wt. 23 000 and is a very potent inhibitor of protein synthesis in the lysate system, with an ID50 of 1.8 ng/ml. This inhibitor has no effect on protein synthesis by Yoshida cells, and has no haemagglutinating properties. 4. Artemia salina ribosomes preincubated with the lectin or with the inhibitor lose their capacity to perform protein synthesis. The proteins seem to act catalytically, since they inactivate a molar excess of ribosomes. 5. The lectin and the inhibitor are somewhat toxic to mice, the LD50 being 316 and 340 micrograms/100 g body wt. respectively.

Journal ArticleDOI
TL;DR: Peptide mapping by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after partial proteolysis by proteases and cyanogen bromide demonstrated that these PBPs are distinct polypeptides.

Journal ArticleDOI
TL;DR: Data indicate that three of the known biological activities of Shiga toxin are associated with a 33,000-dalton substance which can be dissociated into 29,000 and 4,000 to 7,000 daltons components.
Abstract: Shigella dysenteriae 1 (Shiga) toxin was purified from whole-cell lysates by antitoxin affinity column chromatography, radioiodination, and Sephacryl S-200 gel filtration of 125I-labeled affinity column eluates. Two chromatographic peaks were observed. The percentage of radioactivity in peak I samples immunoprecipitated with antitoxin ranged from 95 to 100%. A pool of samples from this first peak contained over 90% of the HeLa-cell-cytotoxic units applied to the column and was enterotoxic for rabbit ileal loops and lethal for rabbits. This radiolabeled material migrated as a single cytotoxic band after nondenaturing polyacrylamide gel electrophoresis, but formed three bands, of 33,000, 29,000, and 4,000 to 7,000 daltons, after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In addition, material estimated as 7,000 daltons by Bio-Gel P-10 chromatography could be generated by treatment of S-200 peak I samples with 8 M urea. Pooled fractions from the second S-200 peak were separable into several low-molecular-weight peaks on a P-10 column. One of these P-10 peaks (7,000 daltons) was 27% immunoprecipitable with antitoxin. These data indicate that three of the known biological activities of Shiga toxin are associated with a 33,000-dalton substance which can be dissociated into 29,000- and 4,000- to 7,000-dalton components.

Journal ArticleDOI
01 Dec 1980-Diabetes
TL;DR: These data demonstrate that in alkaline solution, the NaB3H4-reducible breakdown products of nonenzymatically glycosylated proteins are adsorbed to m-aminophenyl boronic acid immobilized on Bio-Gel P-6, while nonglycosylation amino acids are not.
Abstract: An affinity chromatography system has been developed that retains glycosylated amino acids and peptides. Using this system, synthetic 14C-glycosylated lysine (reduced with NaB3H4) was completely separated from a mixture of reduced 14C-glycosylated lysine and unmodified 3H-lysine. Amino acid analysis of the retained peak from hydrolyzed human diabetic hemoglobin previously reduced with NaB3H4 revealed an equimolar mixture of glycosylated valine and glycosylated lysine, in agreement with previously published data obtained using other methodologies. These data demonstrate that in alkaline solution, the NaB3H4-reducible breakdown products of nonenzymatically glycosylated proteins are adsorbed to m-aminophenyl boronic acid immobilized on Bio-Gel P-6, while nonglycosylated amino acids are not. This affinity chromatography system should facilitate the rapid evaluation of nonenzymatic glycosylation in a large number of diabetic tissues. Levels of retained compounds in urine from diabetic and normal patients were determined by measuring ninhydrin-positive material. Amino acid analysis of NaB3H4-reduced hydrolysates of these peaks showed that glycosylated lysine was the major borohydride-reducible adduct present (67%--86%). Linear regression analysis showed that the quantity of excreted compounds in normals correlated with body weight (r = 0.63). The mean level (mumol leucine-equivalent/24 h/kg body weight) in diabetics was over 1.5 times that found in urine from normal subjects (P < 0.005).

Journal Article
TL;DR: The relative agglutinating potency of the different strains of amoebae was investigated and among the oligosaccharides of N-acetylglucosamine, the trimer and tetramer were the most potent inhibitors.
Abstract: A lectin (carbohydrate binding protein) has been found in extracts of a number of axenically grown trophozoites of Entamoeba histolytica strains. The strains grown in Diamond's TYI-S-33 media were HK-9, 200:NIH and HM-1: IMSS. Strain HU-1: MUSC (HSC) was grown monoxenically in the same medium. The amoeba lectin agglutinates glutaraldehyde-fixed red blood cells. This activity is pH dependent, heat and oxidation sensitive and is destroyed by proteolysis upon auto-incubation. The relative agglutinating potency of the different strains was investigated. Strain HSC had the highest specific activity (210 units/mg protein) and strain HM-1 the lowest (14 units/mg). One unit of haemagglutinating activity is defined as the amount of leetin present in 1 ml of extract which will agglutinate 1 ml of 4 per cent red blood cells. Upon subcellular fractionation of the lectin present in extracts of strain HK-9, two thirds of the activity were detected in the soluble, non-sedimentable (100,000 x g, 60 min) fraction. Partial hydrolysate of chitin was found to inhibit the haemagglutinating activity. Among the oligosaccharides of N-acetylglucosamine, the trimer and tetramer were the most potent inhibitors. The lectin was purified approximately 300 fold by a one step affinity chromatography on a chitin column. The loading and elution from the column were based on the pH dependence of the lectin activity.

Journal ArticleDOI
TL;DR: An enzyme-linked immunosorbent assay (ELIZA) was developed for screening production of monoclonal antibodies with specificity for surface membrane components on human mononuclear cells and allowed rapid, reproducible, and efficient detection of antibody producing hybridomas.

Journal ArticleDOI
TL;DR: A temperature-sensitive single-stranded DNA-binding protein has been purified from mutant Escherichia coli (ssb-1) cells by use of affinity chromatography on blue dextran-Sepharose, confirming that the ssb mutation is in the structural gene.

Journal ArticleDOI
TL;DR: The activity of aminopeptidase A was not affected by sulfhydryl agents, S-S dissociating agents and serine proteinase inhibitor, but was inhibited strongly by metal chelating agents, and enhanced by alkaline earth metals.

Journal ArticleDOI
TL;DR: At pH 6, the proteinase exhibits a remarkable stability even in 6 M urea, and the temperature and the pH stability of the enzyme have been determined.

Journal ArticleDOI
TL;DR: A lectin (carbohydrate-binding protein) has been found in extracts of a number of axenically grown trophozoites of Entamoeba histolytica strains.
Abstract: A lectin (carbohydrate-binding protein) has been found in extracts of a number of axenically grown trophozoites of Entamoeba histolytica strains. The strains grown in TYI-S-33 medium (Diamond et al., Trans. R. Soc. Trop. Med. Hyg. 72: 431-432, 1978) were HK-9, 200:NIH, and HM-1:IMSS. Strain HU-1:MUSC (HSC) was grown monoxenically in the same medium. The amoebic lectin agglutinated glutaraldehyde-fixed erythrocytes. This activity was pH dependent and heat and oxidation sensitive, and was destroyed by proteolysis upon autoincubation. The relative agglutinating potency of the different strains of amoebae was investigated. Strain HSC had the highest specific activity (210 U/mg of protein), and strain HM-1 had the lowest (14 U/mg). One unit of hemagglutinating activity is defined as the amount of lectin present in 1 ml of extract which will agglutinate 1 ml of 4% erythrocytes. Upon subcellular fractionation of the lectin present in extracts of strain HK-9, two-thirds of the activity was detected in the soluble, nonsedimentable (100,000 × g, 60 min) fraction. Partial hydrolysate of chitin was found to inhibit the hemagglutinating activity. Among the oligosaccharides of N-acetylglucosamine, the trimer and tetramer were the most potent inhibitors. The lectin was purified approximately 300-fold by a one-step affinity chromatography on a chitin column. The loading and elution from the column were based on the pH dependence of the lectin activity.