Showing papers on "Affinity chromatography published in 1986"

Purification and biochemical characterization of the promoter-specific transcription factor, Sp1

Abstract: The biochemical analysis of cellular trans-activators involved in promoter recognition provides an important step toward understanding the mechanisms of gene expression in animal cells. The promoter selective transcription factor, Sp1, has been purified from human cells to more than 95 percent homogeneity by sequence-specific DNA affinity chromatography. Isolation and renaturation of proteins purified from sodium dodecyl sulfate polyacrylamide gels allowed the identification of two polypeptides (105 and 95 kilodaltons) as those responsible for recognizing and interacting specifically with the GC-box promoter elements characteristic of Sp1 binding sites.

Affinity purification of sequence-specific DNA binding proteins.

Abstract: We describe a method for affinity purification of sequence-specific DNA binding proteins that is fast and effective. Complementary chemically synthesized oligodeoxynucleotides that contain a recognition site for a sequence-specific DNA binding protein are annealed and ligated to give oligomers. This DNA is then covalently coupled to Sepharose CL-2B with cyanogen bromide to yield the affinity resin. A partially purified protein fraction is combined with competitor DNA and subsequently passed through the DNA-Sepharose resin. The desired sequence-specific DNA binding protein is purified because it preferentially binds to the recognition sites in the affinity resin rather than to the nonspecific competitor DNA in solution. For example, a protein fraction that is enriched for transcription factor Sp1 can be further purified 500- to 1000-fold by two sequential affinity chromatography steps to give Sp1 of an estimated 90% homogeneity with 30% yield. In addition, the use of tandem affinity columns containing different protein binding sites allows the simultaneous purification of multiple DNA binding proteins from the same extract. This method provides a means for the purification of rare sequence-specific DNA binding proteins, such as Sp1 and CAAT-binding transcription factor.

Characterization of highly immunogenic p66/p51 as the reverse transcriptase of HTLV-III/LAV

Abstract: Approximately 80 percent of all human sera that react with antigens of HTLV-III, the etiologic agent of the acquired immune deficiency syndrome (AIDS), recognize protein bands at 66 and 51 kilodaltons. A mouse hybridoma was produced that was specific to these proteins. Repeated cloning of the hybridoma did not separate the two reactivities. The p66/p51 was purified from HTLV-III lysates by immunoaffinity chromatography and subjected to NH2-terminal Edman degradation. Single amino acid residues were obtained in 17 successive degradation cycles. The sequence determined was a perfect translation of the nucleotide sequence of a portion of the HTLV-III pol gene. The purified p66/51 had reverse transcriptase activity and the monoclonal immunoglobulin G specifically removed the enzyme activity from crude viral extract as well as purified enzyme.

Analysis of a Human Tumor-associated Glycoprotein (TAG-72) Identified by Monoclonal Antibody B72.3

Abstract: Monoclonal antibody B72.3 binds a high-molecular-weight tumor-associated glycoprotein identified as TAG-72. This study reports the partial purification and characterization of TAG-72 from a xenograft of a human carcinoma cell line, LS-174T, which expresses high levels of this antigen. The tumor homogenate was initially fractionated by Sepharose CL-4B chromatography. The high-molecular-weight TAG-72, found in the exclusion volume, was then subjected to two sequential passages through B72.3 antibody affinity columns. At each step of the procedure, TAG-72 content was quantitated using a competition radioimmunoassay, and the degree of purification was expressed as the ratio of antigen in units to total protein. The three-step procedure produced a purification of TAG-72 with minimal contamination by other proteins as shown by polyacrylamide gel electrophoresis, followed by staining with Coomassie Blue or periodic acid/Schiff reagent. The density of affinity-purified TAG-72, as determined by cesium chloride gradient ultracentrifugation, was found to be 1.45 g/ml. This density determination, together with the high molecular weight of TAG-72, its resistance to Chondroitinase digestion, the presence of blood group-related oligosaccharides, and sensitivity to shearing into lower-molecular-weight forms suggest that TAG-72 is a mucin-like molecule.

Purification and characterization of a membrane protein (gp45-70) that is a cofactor for cleavage of C3b and C4b.

Abstract: Based on preliminary evidence indicating that a cell-associated protein of U937 (a human monocyte-like cell line) possessed cofactor activity and was not the C3b/C4b receptor, we sought to further characterize this protein. A sequential four-column purification procedure was devised that includes C3(H2O) affinity chromatography to isolate in reasonable yields and purity a cell-associated protein of U937 and several other human cell lines. Based on its pattern and Mr on SDS-PAGE, acidic pI, and ligand specificity, it is identical to a recently described C3(H2O) or C3b-binding membrane glycoprotein of human PBL and cell lines; having no presently identified function, it was termed gp45-70. After purifying this protein, we determined its functional capabilities and compared them to those of the other complement proteins with regulatory activity directed at components comprising the C3 convertases. This protein was the most efficient (50 times that of H) yet-described cofactor for the I-mediated first cleavage of C3b. It also was a cofactor for the first cleavage of C4b, but was not as efficient as C4bp. The second cleavage of C3b and C4b was not efficiently mediated. It had no ability to accelerate decay in the classical or alternative pathway C3 convertases. Based on this unique activity profile and ability to be surface labeled, we have renamed this molecule membrane cofactor protein (MCP). We suggest that this protein plays a major role in preventing autologous complement activation.

DNA helicase activity of SV40 large tumor antigen.

Abstract: Large tumor antigen (T antigen) was extracted from SV40-infected African Green Monkey cells and purified to homogeneity by immunoaffinity chromatography. The purified T antigen preparations unwind DNA duplices of greater than 120 bp in a reaction which is dependent on magnesium ions and ATP hydrolysis. Based on these and other properties of the reaction we classify this newly discovered enzymatic activity as a eukaryotic DNA helicase. The helicase and the known ATPase function of T antigen cosediment with the mono- or dimeric 4-6 S form of T antigen, but not with higher T antigen aggregates. The helicase activity seems to be an intrinsic function of SV40 T antigen. First, several different T antigen-specific monoclonal antibodies interfere with the DNA unwinding activity; monoclonals which are known to reduce the T antigen-specific ATPase most strongly inhibited the helicase reaction. Second, mutant T antigens with impaired ATPase function also showed a reduced DNA unwinding activity.

A single polypeptide possesses the binding and transcription activities of the adenovirus major late transcription factor.

Abstract: A simple approach has been developed for the unambiguous identification and purification of sequence-specific DNA-binding proteins solely on the basis of their ability to bind selectively to their target sequences. Four independent methods were used to identify the promoter-specific RNA polymerase II transcription factor MLTF as a 46-kilodalton (kDa) polypeptide. First, a 46-kDa protein was specifically cross-linked by UV irradiation to a body-labeled DNA fragment containing the MLTF binding site. Second, MLTF sedimented through glycerol gradients at a rate corresponding to a protein of native molecular weight 45,000 to 50,000. Third, a 46-kDa protein was specifically retained on a biotin-streptavidin matrix only when the DNA fragment coupled to the matrix contained the MLTF binding site. Finally, proteins from the most highly purified fraction which were eluted and renatured from the 44- to 48-kDa region of a sodium dodecyl sulfate-polyacrylamide gel exhibited both binding and transcription-stimulatory activities. The DNA-binding activity was purified 100,000-fold by chromatography through three conventional columns plus a DNA affinity column. Purified MLTF was characterized with respect to the kinetic and thermodynamic properties of DNA binding. These parameters indicate a high degree of occupancy of MLTF binding sites in vivo.

Purification of a factor from human placenta that stimulates capillary endothelial cell protease production, DNA synthesis, and migration.

Abstract: A protein that stimulates the production of plasminogen activator and latent collagenase in cultured bovine capillary endothelial cells has been purified 10(6)-fold from term human placenta by using a combination of heparin affinity chromatography, ion-exchange chromatography, and gel chromatography. The purified molecule has a molecular weight of 18,700 as determined by NaDodSO4/PAGE under both reducing and nonreducing conditions. The purified molecule stimulates the production of plasminogen activator and latent collagenase in a dose-dependent manner between 0.1 and 10 ng of protein/ml. The purified protein also stimulates DNA synthesis and chemotaxis in capillary endothelial cells in the same concentration range. Thus, this molecule has all of the properties predicted for an angiogenic factor.

The released interleukin 2 receptor binds interleukin 2 efficiently.

Abstract: The released interleukin 2 receptor (IL 2R) molecule was characterized in order to clarify its biochemical structure and to determine its functional capacity Enzymatic digestions demonstrated that the released IL 2R, like the cell surface IL 2R, is a complex glycoprotein, modified by the addition of both N- and O-linked carbohydrates and sialic acid residues It has a peptide backbone that is approximately 10 Kd smaller than that of its membrane-associated counterpart Affinity chromatography demonstrated that released IL 2R from either an HTLV-I-positive T cell line (HUT-102) or PHA-activated normal peripheral lymphocytes binds efficiently to purified recombinant IL 2 Furthermore, the interaction between the growth factor and the released receptor does not appear to require any accessory molecules These observations suggest a potentially significant role for the released IL 2R in the regulation of IL 2-dependent lymphocyte functions

Autocrine Growth Stimulation of the MCF 7 Breast Cancer Cells by the Estrogen-Regulated 52 K Protein

Abstract: The growth of MCF 7 human breast cancer cells is stimulated in vitro by estradiol (E2) and we have previously shown that estrogen-regulated glycoproteins released into the culture medium can partly mimick this effect. In this paper, we evaluate the mitogenic activity of the 52 K glycoprotein, which is a major E2-stimulated protein released by MCF 7 cells. The 52 K protein was purified 600-fold by affinity chromatography on Concahavalin A and an anti-52 K monoclonal antibody Sepharose columns. The 99% purified 52 K protein fraction stimulated the growth of estrogen-deprived MCF 7cells. A mean 1.7-fold increase was obtained with nanomolar concentrations of seven different preparations of 52 K protein. This stimulation represented 40% of the mitogenic effect of E2. Both the 52 K protein and E2 induced microvilli at the cell surface but the effect of the 52 K protein ocurred earlier. Other putative growth factors which are also stimulated by E2 and observed by [35SJcysteine labeling did not comigrate with the...

Purification from a human hepatoma cell line of a basic fibroblast growth factor-like molecule that stimulates capillary endothelial cell plasminogen activator production, DNA synthesis, and migration.

Abstract: A 17,500-dalton protein which stimulates plasminogen activator production in cultured bovine capillary endothelial cells has been purified from a SK-Hep-1 human hepatoma cell lysate by using heparin affinity chromatography and fast protein-liquid ion exchange chromatography. The purified molecule stimulated plasminogen activator production in a dose-dependent manner between 0.01 and 1 ng/ml. It also stimulated collagenase synthesis, DNA synthesis, and motility in capillary endothelial cells in the same concentration range. This molecule was identified as a basic fibroblast growth factor-like molecule on the basis of its biological activity, its affinity for heparin-Sepharose, and its cross-reactivity with a polyclonal antibody raised against the human placental basic fibroblast growth factor.

Mr 26,000 antigen of Schistosoma japonicum recognized by resistant WEHI 129/J mice is a parasite glutathione S-transferase.

Abstract: Mice of the inbred strain 129/J bred at this Institute (WEHI 129/J) are relatively resistant to chronic infection with the parasitic helminth Schistosoma japonicum. In contrast to more permissive mouse strains such as BALB/c, the WEHI 129/J mice are high responders to a Mr 26,000 adult worm antigen designated Sj26. Cloned cDNAs corresponding to Sj26 have been identified in a S. japonicum phage lambda gt11 amp3 expression library, and their nucleotide sequences have been deduced. The predicted amino acid sequence of the antigen specified by these cDNAs shows striking homology with class mu isozymes of mammalian glutathione S-transferases (RX:glutathione R-transferase, EC 2.5.1.18). Extracts of adult worms contain glutathione S-transferase activity, and affinity chromatography of enzyme activity on glutathione columns leads to the purification of a Mr 26,000 molecule that comigrates with Sj26. Although vaccination studies in mice with a beta-galactosidase-Sj26 fusion protein from Escherichia coli are encouraging, more immunogenic preparations of the antigen are likely to be required to establish the utility of Sj26 as a model vaccine.

Biochemical characterization of a soluble form of the 53-kDa monocyte surface antigen

Abstract: Two monoclonal antibodies, MEM-15 and MEM-18, were prepared which recognize a monocyte 53-kDa antigen. A soluble form of this antigen was found in most normal sera and in urine of some nephrotic patients. Milligram amounts of this glycoprotein were isolated by immunoaffinity chromatography from urine and used for quantitative amino acid and carbohydrate analysis and N-terminal amino acid sequencing. The reactivity of the isolated antigen with several previously described monoclonal antibodies indicates that it is the antigen previously called MY-4 or MY-23. A significant homology exists between the sequenced N-terminal portion of the antigen and sequences found in the kinase-related transforming protein src and in the precursor of epidermal growth factor.

Characterization of the CA 125 Antigen Associated with Human Epithelial Ovarian Carcinomas

Abstract: The murine monoclonal antibody OC125 reacts with an antigenic determinant (CA 125) found on a high-molecular-weight glycoprotein complex present in the serum of greater than 80% of women with epithelial ovarian cancer. The antigen expressing CA 125 (CA 125 antigen) isolated from the sera of ovarian carcinoma patients was shown by gel electrophoresis, molecular size exclusion chromatography, and buoyant density ultracentrifugation to have similar immunological and physical characteristics to antigen isolated from an ovarian cancer cell line (OVCA 433) and human milk. A composite sodium dodecyl sulfate:2.5% polyacrylamide:1.0% agarose gel resolved the CA 125 activity from the three sources of antigen into disperse bands of similar electrophoretic mobilities with apparent masses of 200,000 to 1 million daltons. The buoyant densities of the CA 125 antigen complexes from human serum, OVCA 433 cells, and human milk were in the range of 1.36 to 1.46 g/ml. Isolation of CA 125 antigen of higher purity from OVCA 433 supernatant was achieved by a series of steps including OC125 immunoaffinity chromatography. Subsequent resolution of this purified CA 125 antigen complex by sodium dodecyl sulfate:polyacrylamide gel electrophoresis gave rise to a band at approximately 200,000 daltons. Treatment of the CA 125 antigen from OVCA 433 cells with 10 mm periodic acid resulted in no loss of activity. Reduction and alkylation in 6 m guanidine-HCI or treatment at 100°C for 20 min resulted in complete loss of activity. Exoglycosidase treatments did not result in loss of activity, whereas protease digestion eradicated all activity. These data strongly suggest that the CA 125 antigenic determinant is composed of, at least in part, conformationally dependent peptide.

Isolation of a human erythrocyte membrane protein capable of inhibiting expression of homologous complement transmembrane channels

Abstract: Erythrocytes are poorly lysed by homologous complement, whereas they are readily lysed by heterologous complement. This phenomenon had been attributed to an interference by the cell surface with the action of complement components C8 and C9. To isolate the responsible membrane constituent, detergent-solubilized human erythrocyte (EH) membranes were subjected to affinity chromatography by using human C9-Sepharose. The isolated protein had a mass of 38 kDa and, incorporated into liposomes, was highly effective in inhibiting complement-mediated channel expression, including the C5b-8, membrane attack complex, and tubular polymer of C9 channels. Antibody produced to the 38-kDa protein caused a 20-fold increase in reactive lysis of EH by isolated C5b6, C7, C8, and C9. The antibody did not enhance C5b-7 uptake, but it affected C9 binding to the target cell membrane. Antibody to human decay-accelerating factor, used as a control, had no effect on reactive lysis of EH. Anti-38-kDa protein did not enhance the action on EH of C8 and C9 from other species, indicating that the action of this regulatory protein is species specific. It was therefore termed homologous restriction factor (HRF). Blood cells other than erythrocytes, such as polymorphonuclear leukocytes, also exhibited cell-surface HRF activity. In immunoblots of freshly isolated EH membranes, anti-38-kDa HRF detected primarily a 65-kDa protein, suggesting that the 38-kDa protein constitutes an active fragment of membrane HRF. Because of the specific binding reaction observed between HRF and C8 or C9, HRF was tested with anti-human C8 and anti-human C9. A limited immunochemical relationship of HRF to C8 and C9 could be established and solid-phase anti-C9 proved an efficient tool for the isolation of HRF from solubilized EH membranes.

Exocellular components of Paracoccidioides brasiliensis: identification of a specific antigen.

Abstract: Yeast forms of Paracoccidioides brasiliensis grown in liquid medium produced exocellular components. Immunodiffusion reactions and immunoprecipitations of 131I-radiolabeled antigenic components with sera from patients having paracoccidioidomycosis (PCM) were used to monitor the isolation of specific constituents. Components having the main antigenic activity (fCon A) were isolated by exclusion from a Bio-Gel P30 column, followed by successive binding of eluted material to a Sepharose-concanavalin A column, and elution. The product contained, from sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, a minor 43,000-molecular-weight (MW) component (gp43), a polydisperse high-MW glycoconjugate, and a diffusely migrating 55,000-MW glycoprotein (gp55). Other components, including a 72,000-MW glycoprotein, were irregularly expressed. The high-MW glycoconjugate complex contained, on the basis of methylation and 13C nuclear magnetic resonance data, a branched structure of mainly mannopyranosyl units. These were nonreducing ends, 6-O-, 2-O-, and 2,6-di-O-substituted, and the specific rotation of +16 degrees indicated that the glycosidic configurations of the units were alpha and beta in a ratio of ca. 1:1 (concanavalin A binding indicated that nonreducing ends or 2-O-substituted units or both of alpha-D-mannopyranose were present). A small proportion of nonreducing end units of D-galactopyranose were also present in this polysaccharide. gp55 is a glycoprotein containing a complex carbohydrate moiety with fucose, mannose, galactose, and glucose, either as terminal nonreducing units or substituted in positions indicated by methylation data. Both PCM and normal human sera precipitated the high-MW glycoconjugate from 131I-labeled fCon A preparations, whereas gp55 was unreactive with human sera. gp43 was a specific antigenic component of P. brasiliensis culture filtrates which could be isolated in a pure form by gel filtration column chromatography (Sephadex G150) or by Sepharose-patient immunoglobulin G affinity chromatography. 131I-labeled gp43 reacted equally well with 10 PCM sera and hyperimmune rabbit serum against the band E antigen of Yarzabal at a 10(-3) dilution. At the same dilution, no reaction was detected with sera from normal individuals and from patients with other mycoses. Similarly, only PCM sera and the hyperimmune anti-E serum gave precipitin lines with gp43 in the less sensitive immunodiffusion tests. gp43 consisted of three components, with pI 6.7, 6.4 and 6.2, all of which reacted with PCM serum. Images

Purification and characterization of a novel, oligomeric, plasminogen kringle 4 binding protein from human plasma: tetranectin.

Abstract: Purification of alpha 2-plasmin inhibitor (alpha 2PI) from human plasma by affinity chromatography on plasminogen-Sepharose resulted in copurification of a contaminating protein with Mr 17,000 as judged by sodium dodecyl sulphate/polyacrylamide gel electrophoresis. This contaminating protein could not be removed from the purified alpha 2-PI preparation by several types of gel chromatography applied. The use of the kringle 1-3 part of plasminogen, K(1 + 2 + 3), bound to Sepharose for affinity chromatography, instead of plasminogen-Sepharose, resulted in an alpha 2PI preparation without this contaminant. The contaminating protein was found to interact specifically with the kringle 4 part of plasminogen (K4) and not with K(1 + 2 + 3) or miniplasminogen. The K4-binding protein was purified by ammonium sulphate precipitation, affinity chromatography on K4-Sepharose, ion-exchange chromatography and gel filtration on AcA 34. The relative molecular mass of the protein (Mr 68 000) was estimated by gel filtration. This suggests a tetrameric protein composed of four subunits (Mr 17,000), that are dissociated by 1% sodium dodecyl sulphate. Dissociation into subunits was also demonstrated by gel filtration in the presence of 6 M guanidine hydrochloride. A specific antibody was raised in rabbits against the purified protein and this antibody was shown not to react with any known fibrinolytic components. The pI of the K4-binding protein was found to be 5.8. The first three N-terminal amino acids were determined to be Glu-Pro-Pro. The concentration of the protein in plasma was estimated to be 0.20 +/- 0.03 microM (15 +/- 2 mg/l). The electrophoretic mobility of the K4-binding protein was shown by crossed immunoelectrophoresis to be influenced by the presence of Ca2+, EDTA and heparin. The protein was found to enhance plasminogen activation catalyzed by tissue-type plasminogen activator (t-PA) in the presence of poly(D-lysine). The protein appeared to be a novel plasma protein tentatively called 'tetranectin'.

The Purification and Characterization of Rat Gamma Interferon by Use of Two Monoclonal Antibodies

Abstract: Two mouse monoclonal antibodies, designated DB-1 and DB-2, were isolated and used for the purification and characterization of recombinant rat interferon gamma (rRIF-gamma) derived from Chinese hamster ovary (CHO) cells. The two antibodies belong to different classes (DB-1 is an IgG1 and DB-2 an IgA) and display similar epitope specificities as shown in competition binding experiments. Both antibodies, raised against rRIF-gamma, exhibited high affinity for rat and mouse gamma interferon and efficiently neutralized the antiviral activity of both animal interferon species. Affinity chromatography analysis showed that a column with immobilized DB-1 was capable of complete binding of rat and mouse gamma interferon, both natural and recombinant DNA-derived. As visualized by SDS-polyacrylamide gel electrophoresis and Western blot analysis, the purified rRIF-gamma preparation consisted of at least seven molecular forms with Mr values ranging between 14 000 and 25 000, with a relative abundance of a 18 000 Mr protein. Gel permeation chromatography of crude rRIF-gamma gave coincident peaks of rRIF-gamma proteins (all different forms) and interferon activity corresponding to a Mr value of 45 000. The results suggest that the molecular heterogeneity was due to differential glycosylation and was not the consequence of a proteolytic degradation process.