Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Affinity purification”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1989

Overproduction, affinity purification and characterization of 65-kDa protein of Mycobacterium leprae in Escherichia coli.

The 65-kDa protein of Mycobacterium leprae was produced in an Escherichia coli strain carrying a plasmid harboring the recloned gene coding for the protein. The protein was purified through affinity chromatography prepared with the IgG fraction of a monoclonal antibody which was prepared against the 65-kDa protein. The purified 65-kDa protein also reacted immunologically with the monoclonal antibody IIIE9, which recognizes the epitope for M. leprae, prepared by Buchanan, et al. BALB/c mice were inoculated with M. leprae and 4 months later were skin tested with the purified 65-kDa protein. Gross changes were observed at the skin-test site. The role of the protein in protective immunity against M. leprae foot pad infection in mice was also studied.

Animals↗
PubMed1992

Affinity purification of proteinases by a combination of immobilized peptidyl aldehyde and semicarbazone.

D-Phe-Phe-argininal semicarbazone and Tyr-Gly-Gly-Phe-Leu-Arg-argininal semicarbazone were prepared using the solution phase synthesis method and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The tripeptide and heptapeptide semicarbazones were individually immobilized on affi-Gel 15 resulting in two affinity columns called S3 and S7, respectively. A third affinity column was obtained by hydrolysing the semicarbazone moiety in column S3 to aldehyde (column A3). Serine proteinases such as trypsin or rat plasma kallikrein almost quantitatively bind to either S3 or A3 affinity columns. Under optimized conditions, more than 97% of trypsin bound to both columns S3 and A3. At a lower ionic strength and higher pH, 80-85% of rat plasma kallikrein bound to the same columns. Elution of both enzymes was achieved using mild conditions at near neutral pH and in the presence of a small amount of denaturant. Both proteinases were identified and characterized by high-performance liquid chromatography, sodium dodecylsulphate polyacrylamide gel electrophoresis and by their substrate specificity and inhibition profiles. A single purification (six-to seven-fold) step using either column S3 or A3 allowed the preparation of pure trypsin from commercial sources. Starting from rat plasma partially purified by a phenyl boronate column, fractionation on the S3 column allowed approximately an 87-fold purification of rat plasma kallikrein. However, serial purification of rat plasma kallikrein on column S7 followed by column A3 resulted in a purification factor of about 455.

Aldehydes↗
PubMedDate not supplied

Affinity purification of fusion chaperonin Cpn60-(His)(6) from thermophilic bacterium Bacillus strain MS and its use in facilitating protein refolding and preventing heat denaturation.

The cpn60 gene from Bacillus strain MS, which is highly homologous to Bacillus stearothermophilus, was cloned. Cpn60 with a hexahistidine affinity tag (His)(6) fused to its C-terminus (cpn60-(His)(6)) was overproduced in Escherichia coli. Cpn60-(His)(6) was expressed in a soluble form in E. coli. and purified to homogeneity in a single step by nickel chelate affinity chromatography. Cpn60-(His)(6) formed a tetradecamer and had ATPase activity. Cpn60-(His)(6) mediated refolding of guanidine hydrochloride unfolded pig heart malic dehydrogenase (MDH) and Thermus flavus MDH at 25 and 70 degrees C, respectively, in an ATP-dependent manner. In addition, cpn60-(His)(6) prevented heat denaturation of pig heart MDH and T. flavus MDH at 30 and 80 degrees C, respectively, in an ATP-dependent manner. Therefore, cpn60-(His)(6) facilitates protein refolding and prevents heat denaturation of proteins across a wide temperature range.

Bacillus↗
PubMed1988

High-level synthesis in Escherichia coli of functional cap-binding eukaryotic initiation factor eIF-4E and affinity purification using a simplified cap-analog resin.

Numerous studies have established the important role that eukaryotic initiation factor-4E (eIF-4E) plays during protein biosynthesis. However, biochemical characterization of eIF-4E has proved difficult, mainly because of its low abundance in cells. To facilitate studies on eIF-4E, we have overexpressed Saccharomyces cerevisiae eIF-4E in Escherichia coli. The isolation of eIF-4E was simplified by using a cap-analog affinity matrix (agarose resin) that is considerably less demanding to prepare than those previously reported. We describe a simple and rapid purification scheme that can yield 2-5 micrograms of a homogenous and active preparation of eIF-4E from 1 ml of E. coli culture. E. coli-expressed eIF-4E is active as determined by its ability to bind the cap structure. The results demonstrate that the cap-binding activity of eIF-4E is not dependent on the presence of other proteins that are present at low levels in eIF-4E preparations isolated from eukaryotic cells.

Base Sequence↗
PubMedDate not supplied

Affinity purification of 101 residue rat cpn10 using a reversible biotinylated probe.

The purification of large synthetic peptides using conventional separation techniques often results in poor yields and homogeneity due to the accumulation of chromatographically similar deletion and truncated impurities. We have developed a highly effective synthetic strategy and one-step purification procedure that is based on (i) the application of single coupling using HBTU/HOBt activation to reduce incomplete couplings, (ii) the use of N-(2-chlorobenzyloxycarbonyloxy)succinimide as a capping agent to terminate deletion sequences and (iii) the N-terminal derivatization of the complete peptidyl-resin with a reversible Fmoc-based chromatographic probe possessing enhanced physico-chemical properties (i.e. hydrophobicity, charge or affinity label). We report the application of a biotinylated probe, activated as the succinimidyl carbonate, for the purification of a 101 residue chaperonin protein from Rattus norvegicus (rat cpn10), previously synthesized using an optimized synthetic protocol. Biotinylated rat cpn10 was separated from underivatized impurities on an immobilized monomeric avidin column. Free rat cpn10 was released from avidin-agarose column with 5% aqueous triethylamine and after desalting by RP-HPLC gave 9.9% recovery. Characterization and assessment of homogeneity was achieved using ESI-MS, CZE and RP-HPLC.

Animals↗
PubMed1991

The affinity purification and characterization of a dehydrogenase from Aspergillus parasiticus involved in aflatoxin B1 biosynthesis.

A two step scheme has been developed for the purification of a dehydrogenase from mycelia of 84 hours old Aspergillus parasiticus (1-11-105 Wh 1), which catalyzes the conversion of norsolorinic acid (NA) to averantin (AVN). The dehydrogenase was purified from cell-free extracts using reactive green 19-agarose and norsolorinic acid-agarose affinity chromatography. The latter affinity matrix was synthesised by attaching norsolorinic acid to omega-aminohexylagarose. The purified protein was shown to be homogenous on non-denaturing polyacrylamide gel electrophoresis. A final purification of 215-fold was achieved. Results of gel filtration chromatography indicated the approximate molecular mass of the native protein to be 140,000 daltons. The isoelectric point of the protein was about 5.5 as determined by chromatofocusing. The reaction catalyzed by the dehydrogenase was optimum at pH 8.5 and between 25 degrees to 35 degrees C. The Km of the enzyme for NA and NADPH was determined to be 3.45 microM and 103 microM respectively.

Aflatoxin B1↗
PubMed1991

Affinity purification and characterization of 2,4-dichlorophenol hydroxylase from Pseudomonas cepacia.

2,4-Dichlorophenol hydroxylase, a flavoprotein monooxygenase from Pseudomonas cepacia grown on 2,4-dichlorophenoxyacetic acid (2,4-D) as the sole source of carbon, was purified to homogeneity by a single-step affinity chromatography on 2,4-DCP-Sepharose CL-4B. The enzyme was eluted from the affinity matrix with the substrate 2,4-dichlorophenol. The enzyme has a molecular weight of 275,000 consisting of four identical subunits of molecular weight 69,000 and requires exogenous addition of FAD for its complete catalytic activity. The enzyme required an external electron donor NADPH for hydroxylation of 2,4-dichlorophenol to 3,5-dichlorocatechol. NADPH was preferred over NADH. The enzyme had Km value of 14 microM for 2,4-dichlorophenol, and 100 microM for NADPH. The enzyme activity was significantly inhibited by heavy metal ions like Hg2+ and Zn2+ and showed marked inhibition with thiol reagents. Trichlorophenols inhibited the enzyme competitively. The hydroxylase activity decreased as a function of increasing concentrations of Cibacron blue and Procion red dyes. The apoenzyme prepared showed complete loss of FAD when monitored spectrophotometrically and had no enzymatic activity. The inactive apoenzyme was reconstituted with exogenous FAD which completely restored the enzyme activity.

Apoenzymes↗
PubMed1995

Affinity purification of proteoglycans that bind to the amyloid protein precursor of Alzheimer's disease.

The binding of the amyloid protein precursor (APP) to heparan sulfate proteoglycans has been shown to stimulate the neurite-promoting activity of APP. In this study, proteoglycans that bind with high affinity to APP were characterized. Conditioned medium from cultures of postnatal day 3 mouse brain cells was applied to an affinity column containing a peptide homologous to a heparin-binding domain of APP. A fraction 17-fold enriched in proteoglycans was recovered by elution with a salt gradient. APP bound saturably and with high affinity to the affinity-purified proteoglycan fraction. Scatchard analysis of the binding showed that APP bound to high- and low-affinity sites with equilibrium dissociation constants of 1.4 x 10(-11) and 6.5 x 10(-10) M, respectively. APP, in conjunction with the affinity-purified proteoglycan fraction, promoted neurite outgrowth. The affinity-purified proteoglycan fraction contained a heparan sulfate proteoglycan and a chondroitin sulfate proteoglycan. Digestion of the affinity-purified fraction with heparitinase I revealed a core protein of 63-69-kDa molecular mass, whereas digestion with chondroitinase ABC revealed a core protein of 100-110 kDa. The results suggest that expression of specific APP-binding proteoglycans may be an important step in the regulation of the neurite outgrowth-promoting activity of APP.

Alzheimer Disease↗
PubMed1984

Affinity purification of mycobacterial polymethyl polysaccharides and a study of polysaccharide-lipid interactions by 1H NMR.

Mycobacterial polymethyl polysaccharides, which bind long-chain fatty acids tightly [Ballou, C.E. (1981) Pure Appl. Chem. 53, 107-112], have been purified on a preparative scale by use of an affinity column packing consisting of (palmitoylamino)alkylsilyl silicate. The relatively large amount of material obtained in this way has allowed a study of the polysaccharide-lipid interactions at millimolar concentrations. The anomeric protons for all of the alpha 1----4-linked hexose units in the mycobacterial methylglucose polysaccharide occur in an envelope centered at delta 5.40, and, on titration with hexadecyltrimethylammonium bromide, the majority of these resonances move upfield to about delta 5.15. This shift is consistent with a change in the polysaccharide from a less ordered chain to one that has a significant proportion of helical conformation, and it is probable that the alkyl chain is included in the coiled portion of the polysaccharide in a manner analogous to the interaction of methylmannose polysaccharide with palmitic acid [Yabusaki, K. K., Cohen, R. E., & Ballou, C. E. (1979) J. Biol. Chem. 254, 7282-7286]. The native methylglucose lipopolysaccharide, which contains several short-chain acyl groups as well as an esterified octanoyl group, has an anomeric proton nuclear magnetic resonance spectrum similar to that of the methylglucose polysaccharide-hexadecyltrimethylammonium bromide complex. This suggests that the acylation stabilizes the polysaccharide chain in the same conformation it assumes when complexed to a long-chain lipid. Thus, acylation of the methylglucose polysaccharide could have an important role in regulating its shape and lipid-binding properties.

Cetrimonium↗
PubMed1996

Affinity purification and binding characteristics of Citrobacter freundii AmpR, the transcriptional regulator of the ampC beta-lactamase gene.

The transcriptional regulator of the Citrobacter freundii ampC beta-lactamase gene, AmpR, was purified as a single SDS/PAGE-gel band by using various techniques, including DNA-Sepharose 4B affinity chromatography. The purified AmpR consisted of a 32.5 kDa monomer that interacted with three operator sequences: two binding sequences, at positions -75 to -70 and -67 to -51 with respect to the transcriptional start site, were located in the LysR motif (-72 to -60), and the third sequence was at position -43 to -38. Equilibrium binding studies raise the possibility that the adjacent operator sequence could exert a positive influence on the ability of AmpR to bind to these sites.

Bacterial Proteins↗
PubMed1998

Aryl thioglycoside-based affinity purification of exo-acting cellulases.

The influence of ligand-coupling chemistry and mobile-phase composition on the interaction of exo-acting cellulases with an immobilized complementary ligand was investigated. p-Aminophenyl 1-thio-beta-D-cellobioside (APTC) was used as a representative affinity ligand to which exo-acting cellulases (cellobiohydrolases, CBHs) preferentially bind. A "crude" cellulase preparation from the fungus Trichoderma reesei served as an enzyme source. The adsorption properties of the two principal exo-acting CBHs in this preparation, CBH I and CBH II, are shown to be distinctly different under several scenarios. Their relative affinities, based on column elution behavior and partition equilibrium experiments, are shown to be highly dependent on the functional groups employed for ligand coupling, the extent of functional group hydrolysis, the composition of the mobile phase, and the inherent nature of the enzymes. The dependency on the chemistry of the supporting matrix was illustrated using agarose supports containing cyanate ester, N-hydroxy-succinimide, and epoxy functional groups. When compared under apparent optimal conditions, the affinity of CBH II for immobilized APTC was approximately 10-fold that of CBH I. However, selective adsorption of CBH I or CBH II can be achieved by adjusting experimental parameters.

Basidiomycota↗
PubMed2000

Affinity purification of heparin-dependent antibodies to platelet factor 4 developed in heparin-induced thrombocytopenia: biological characteristics and effects on platelet activation.

Antibodies to heparin platelet factor 4 (H-PF4) complexes were purified from the plasma of three patients with heparin-induced thrombocytopenia (HIT) using affinity chromatography. From each plasma, the largest amount of antibodies was eluted with 2 M NaCl at pH 7.5 (peak 1) and the remainder was obtained using 0.1 M glycine/0. 5 M NaCl at pH 2.5 (peak 2). In an enzyme-linked immunosorbent assay (ELISA), we then showed that each patient had developed antibodies to PF4 displaying different characteristics. In patient 1, peak 1 IgG reacted almost exclusively with H-PF4 complexes, whereas peak 2 IgG had similar reactivity with PF4 whether or not heparin was present. Patient 2 expressed a mixture of IgA, IgM and IgG and both fractions bound to PF4 alone or to H-PF4 complexes. Finally, IgG in patient 3 only bound to H-PF4 and was unreactive with PF4 alone. Using [14C]-serotonin release assays, the antibodies developed in the three patients and exhibiting the strongest ability to activate platelets with heparin were those having the highest affinity to H-PF4. These results strongly support the hypothesis that HIT antibodies to PF4 are heterogeneous regarding their affinity and specificity for target antigens and this may greatly influence their ability to activate platelets and their pathogenicity.

Anticoagulants↗
PubMed2002

One-step affinity purification of fetuin from fetal bovine serum.

Fetuin is a plasma glycoprotein widely distributed in mammals. It has been used as a model protein for structural analyses and investigations into the biological properties of glycoproteins. A convenient one-step procedure for biospecific isolation of fetuin from fetal bovine serum was developed on the basis of wheatgerm agglutinin (WGA) affinity separation. Two different porous supports, a silica-based material and a polymer-based material, were used for the immobilization of WGA. The prepared WGA adsorbents were characterized and process parameters of the affinity separation of fetuin were investigated and optimized. WGA was immobilized on silica and polymer supports with coupling yields of 99.6 and 99.4% respectively and amounts of coupled ligand of 7.9 and 9.2 mg of WGA/ml respectively. It has been shown that the specific capacities for fetuin were 5.1 mg/ml on WGA-silica, 1.8 mg/ml on WGA-polymer and 4.1 mg/ml on WGA-agarose. All three adsorbents proved to be suitable for the biospecific separation of fetuin. The polymer-based WGA adsorbent was successfully applied in the purification of fetuin from fetal bovine serum in a one-step separation process. The identity and purity of the isolated product was verified by SDS/PAGE. Under optimized conditions up to 21.6 mg of fetuin could be isolated from 1 ml of serum. The procedure described was designed to be easily scaled-up for the production of fetuin.

Animals↗