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PubMed1987

Partial purification and characterization of bovine mammary gland prolactin receptor.

Prolactin (PRL) receptors from the mammary gland of the lactating cow were solubilized with 3-[(3-cholamidopropyl)dimethylamonio]-1-propane sulfonate (CHAPS). Affinite chromatography on human growth hormone (hGH) coupled to Affi-Gel 10 resulted in over 500-fold purification, as compared to microsomal fractions. Scatchard analysis of the binding of hGH indicated an increase in the affinity constant of 2.5-fold after solubilization and of further 2-fold after the affinity purification. The specific binding activity of the affinity-purified fraction was 9000 fmol hGH/mg protein. Complexes of Triton X-100-solubilized receptors with [125I]hGH were analyzed by gel filtration on Sephadex G-150, in the presence of Triton X-100. A minor fraction of the complexes eluted as high molecular weight (Mr) aggregates, whereas a major fraction eluted as a 150 kDa peak. Assuming a contribution of approximately 30% to the Mr by the bound detergent and a hormone: receptor ratio of 1:1 in the complex, a Mr of 80-85 kDa can be calculated for the receptor molecule. Affinity labelling of the receptor with [125I]hGH revealed a Mr of 37 +/- 0.5 kDa (n = 7) for the binding subunit. Specific high Mr aggregates were also observed after crosslinking; however, the size of the labelled species was not affected by reducing agents. Homologous and heterologous competitive binding studies with ovine PRL (oPRL) or hGH revealed a considerably higher affinity for hGH as compared to oPRL. The competitive displacement patterns obtained with oPRL or hGH as tracers were similar, indicating that both hormones bound to the same receptor sites with different affinities. A similar difference in affinity was retained by the affinity-purified receptors.

Affinity Labels↗
PubMed1996

Engineering a de novo-designed coiled-coil heterodimerization domain off the rapid detection, purification and characterization of recombinantly expressed peptides and proteins.

Using the techniques of genetic engineering and the principles of protein de novo design, we have developed a unique affinity matrix protein tag system as a rapid, convenient and sensitive method to detect, purify and characterize newly expressed recombinant peptides or proteins from cell extracts. The method utilizes two de novo-designed linear peptide sequences that can selectively dimerize to form the stable protein motif, the two-stranded alpha-helical coiled-coil. In this method, a recombinant bacterial expression vector pRLDE has been engineered so that one of the dimerization strands (E-coil) is expressed as a C-terminal fusion tag on newly expressed peptides or proteins, while the other (K-coil) is either biotin-labeled for detection in a Western blot-type format or immobilized on an insoluble silica support for selective dimerization affinity chromatography. Recombinantly expressed peptides from Escherichia coli containing the dimerization tag have been produced, detected and purified using this method. The recombinant peptides were easily and clearly identified using the biotin-labeled coil, while the single-step affinity purification results indicated the purity of the affinity purified expressed peptides to be > 95%, as assessed by reversed-phase chromatography. The stability of the dimerization domain also allows for the purified peptide to be left attached to the matrix, thus creating a new peptide-bound column that can be used to study peptide-protein or peptide-ligand interactions. Therefore this system offers a new alternative to existing peptide or protein fusion tags and demonstrates the utility of a de novo-designed system.

Amino Acid Sequence↗
PubMed1990

Partial tolerance in beta-galactosidase-transgenic mice.

A transgenic mouse line was produced which allowed the expression of E. coli beta-galactosidase (beta-Gal) under the regulatory elements of the immunoglobulin heavy chain locus. Expression of the transgene is found in spleen and bone marrow. Upon immunization of the transgenic mice with beta-Gal, a reduced but clearly detectable antibody response was obtained. Affinity purification with sera from immunized transgenic mice suggests that they contain lower affinity antibodies as compared to normal littermates. Transgenic and nontransgenic mice immunized with bovine serum albumin (BSA) alone or as a mixture with beta-Gal gave comparable anti-BSA responses. Immunization with a chemically cross-linked (Gal-BSA)-protein, however, showed a 10- to 30-fold difference in the anti-BSA response. Partial unresponsiveness to beta-Gal in the transgenic mice is best explained by a dominant, peripheral suppression mechanism linked to the antigen-presenting potential of B cells.

Animals↗
PubMed2005

Towards a human proteome atlas: high-throughput generation of mono-specific antibodies for tissue profiling.

A great need exists for the systematic generation of specific antibodies to explore the human proteome. Here, we show that antibodies specific to human proteins can be generated in a high-throughput manner involving stringent affinity purification using recombinant protein epitope signature tags (PrESTs) as immunogens and affinity-ligands. The specificity of the generated affinity reagents, here called mono-specific antibodies (msAb), were validated with a novel protein microarray assay. The success rate for 464 antibodies generated towards human proteins was more than 90% as judged by the protein array assay. The antibodies were used for parallel profiling of patient biopsies using tissue microarrays generated from 48 human tissues. Comparative analysis with well-characterized monoclonal antibodies showed identical or similar specificity and expression patterns. The results suggest that a comprehensive atlas containing extensive protein expression and subcellular localization data of the human proteome can be generated in an efficient manner with mono-specific antibodies.

Animals↗
PubMed1993

Identification of the gene product encoded by ORF UL56 of the human cytomegalovirus genome.

Experiments were undertaken to identify the product of open reading frame (orf) UL56 of human cytomegalovirus (HCMV), the putative homolog of infected cell protein (ICP) 18.5 of herpes simplex virus type 1 (HSV-1) that is thought to be involved in viral nucleocapsid maturation. Northern blotting using a unique fragment of orf UL56 revealed a specific transcript of about 3.0 kb in HCMV-infected fibroblasts early and late postinfection (p.i.). Two overlapping fragments of UL56 were subcloned for procaryotic expression and the recombinant proteins were used for affinity purification of an antibody fraction from human convalescent serum (pab UL56). The affinity purified antibody recognized a polypeptide with an apparent molecular weight of about 130 kDa (p 130) in immunoblots of virions and of infected cell extracts late p.i. Upon treatment of isolated virions with nonionic detergent the p 130 polypeptide separated with the nucleocapsid/tegument fraction. The amino acid sequence of p 130 deduced from the nucleotide sequence exhibited a high homology to ICP 18.5 of HSV-1.

Blotting, Northern↗
PubMed2003

Capillary high-performance liquid chromatography/mass spectrometric analysis of proteins from affinity-purified plasma membrane.

Proteomics analysis of plasma membranes is a potentially powerful strategy for the discovery of proteins involved in membrane remodeling under diverse cellular environments and identification of disease-specific membrane markers. A key factor for successful analysis is the preparation of plasma membrane fractions with low contamination from subcellular organelles. Here we report the characterization of plasma membrane prepared by an affinity-purification method, which involves biotinylation of cell-surface proteins and subsequent affinity enrichment with strepavidin beads. Western blotting analysis showed this method was able to achieve a 1600-fold relative enrichment of plasma membrane versus mitochondria and a 400-fold relative enrichment versus endoplasmic reticulum, two major contaminants in plasma membrane fractions prepared by conventional ultracentrifugation methods. Capillary-HPLC/MS analysis of 30 microg of affinity-purified plasma membrane proteins led to the identification of 918 unique proteins, which include 16.4% integral plasma membrane proteins and 45.5% cytosol proteins (including 8.6% membrane-associated proteins). Notable among the identified membrane proteins include 30 members of ras superfamily, receptors (e.g., EGF receptor, integrins), and signaling molecules. The low number of endoplasmic reticulum and mitochondria proteins (approximately 3.3% of the total) suggests the plasma membrane preparation has minimum contamination from these organelles. Given the importance of integral membrane proteins for drug design and membrane-associated proteins in the regulation cellular behaviors, the described approach will help expedite the characterization of plasma membrane subproteomes, identify signaling molecules, and discover therapeutic membrane-protein targets in diseases.

Cell Line↗
PubMed2000

Antiidiotype antibody against platelet anti-GPIIIa contributes to the regulation of thrombocytopenia in HIV-1-ITP patients.

Patients with human immunodeficiency virus 1-associated immunological thrombocytopenia (HIV-1-ITP) have markedly elevated platelet-bound immunoglobulin (Ig)G, IgM, and C3C4, as well as serum circulating immune complexes (CICs) composed of the same. Affinity purification of IgGs from their CICs with fixed platelets reveals high-affinity antibody (Ab) against platelet glycoprotein (GP)IIIa 49-66, which correlates inversely with their platelet count. However, sera from these patients have little to no anti-GPIIIa activity. To investigate this, we assayed serum, purified serum IgG, and CIC-Ig from these patients. This revealed approximately 150-fold greater Ab activity in purified serum IgG, and approximately 4,000-fold greater reactivity in CIC-IgG. This was shown to be associated with the presence of antiidiotype Ab2 (both IgG and IgM) sequestered in the CIC-IgG. The IgM antiidiotype was predominantly blocking Ab, as demonstrated by specificity for F(ab')(2) fragments of anti-GPIIIa 49-66 of HIV-1-ITP patients and inhibition of reactivity with peptide GPIIIa 49-66, not with a control peptide. The IgM antiidiotype was not polyreactive. Similar measurements were made in nonthrombocytopenic HIV-1-infected patients. Their serum reactivity was not measurable, but serum Ig and CIC-IgG against platelet GPIIIa 49-66 was present, although considerably lower than that found in HIV-1-ITP patients (26- and 35-fold lower, respectively). In addition, their IgM antiidiotype reactivity was 12-fold greater than that found in HIV-1-ITP patients. The IgM antiidiotype Ab titer of both cohorts correlated with in vivo platelet count (r = 0.7, P = 0. 0001, n = 32). To test the in vivo effectiveness of the IgM antiidiotype, thrombocytopenia was induced in mice with 25 microgram of affinity-purified anti-GPIIIa 49-66 (mouse GPIIIa has 83% homology with human GPIIIa and Fc receptors for human IgG1). Maximum effect was obtained at 4-6 h after intraperitoneal injection into Balb/c mice with a platelet count of approximately 30% baseline value. Preincubation of the anti-GPIIIa Ab with control IgM at molar ratios of IgM/IgG of 1:7 before intraperitoneal injection had no effect on the in vivo platelet count, whereas preincubation with patient IgM antiidiotype improved the platelet count to 50-80% of normal. Thrombocytopenia could be reversed after addition of IgM antiidiotype 4 h after induction of thrombocytopenia. Thus, CICs of HIV-1-infected patients contain IgM antiidiotype Ab against anti-GPIIIa, which appears to regulate their serum reactivity in vitro and their level of thrombocytopenia in vivo.

Adult↗
PubMed2003

Separation methods in the analysis of protein membrane complexes.

The separation of membrane protein complexes can be divided into two categories. One category, which is operated on a relatively large scale, aims to purify the membrane protein complex from membrane fractions while retaining its native form, mainly to characterize its nature. The other category aims to analyze the constituents of the membrane protein complex, usually on a small scale. Both of these face the difficulty of isolating the membrane protein complex without interference originating from the hydrophobic nature of membrane proteins or from the close association with membrane lipids. To overcome this difficulty, many methods have been employed. Crystallized membrane protein complexes are the most successful example of the former category. In these purification methods, special efforts are made in the steps prior to the column chromatography to enrich the target membrane protein complexes. Although there are specific aspects for each complex, the most popular method for isolating these membrane protein complexes is anion-exchange column chromatography, especially using weak anion-exchange columns. Another remarkable trend is metal affinity column chromatography, which purifies the membrane protein complex as an intact complex in one step. Such protein complexes contain subunit proteins which are genetically engineered so as to include multiple-histidine tags at carboxyl- or amino-termini. The key to these successes for multi-subunit complex isolation is the idea of keeping the expression at its physiological level, rather than overexpression. On the other hand, affinity purification using the Fv fragment, in which a Strep tag is genetically introduced, is ideal because this method does not introduce any change to the target protein. These purification methods supported by affinity interaction can be applied to minor membrane protein complexes in the membrane system. Isoelectric focusing (IEF) and blue native (BN) electrophoresis have also been employed to prepare membrane protein complexes. Generally, a combination of two or more chromatographic and/or electrophoretic methods is conducted to separate membrane protein complexes. IEF or BN electrophoresis followed by 2nd dimension electrophoresis serve as useful tools for analytical demand. However, some problems still exist in the 2D electrophoresis using IEF. To resolve such problems, many attempts have been made, e.g. introduction of new chaotropes, surfactants, reductants or supporting matrices. This review will focus in particular on two topics: the preparative methods that achieved purification of membrane protein complexes in the native (intact) form, and the analytical methods oriented to resolve the membrane proteins. The characteristics of these purification and analytical methods will be discussed along with plausible future developments taking into account the nature of membrane protein complexes.

Chromatography, Liquid↗
PubMed2000

A modular set of prokaryotic and eukaryotic expression vectors.

A modular series of versatile expression vectors is described for improved affinity purification of recombinant fusion proteins. Special features of these vectors include (i) serial affinity tags (hexahistidine-GST) to yield extremely pure protein even with very low expression rates, (ii) highly efficient proteolytic cleavage of affinity tags under a variety of conditions by hexahistidine-tagged tobacco etch virus (TEV) protease, (iii) PCR cloning design that results in a product of proteolytic cleavage with only one (a single glycine) or two (gly-ala) amino acids at the N-terminus of the protein, and (iv) expression in either Escherichia coli or Saccharomyces cerevisiae. In addition, singly hexahistidine-tagged proteins can be produced for purification under denaturing conditions and some vectors allow addition of five amino acid kinase recognition sites for easy radiolabeling of proteins. To illustrate the use of these vectors, all regulatory components of the yeast GAL regulon, rather than abundant highly soluble proteins, were produced and purified under native or denaturing conditions, and their biological activity was confirmed.

Amino Acid Sequence↗
PubMed2004

Functional folding of a cytoplasmic single-chain variable fragment and its use as elutable protein purification tag.

The variable fragment (Fv) of the monoclonal B1-8 antibody recognizes 3-nitro-4-hydroxy-phenylacetate (NP) and 5-iodo-NP (NIP) allowing for the affinity purification of the respective B cell antigen receptor with NP-sepharose and its specific elution with NIP-capronic acid (NIPcap). We generated an intracellular single-chain B1-8 Fv (iscFv), fused it to the N-terminus of the regulatory subunit (p85alpha) of phosphatidylinositol-3-kinase (PI3K) (isc-p85alpha), and examined the potential of this iscFv to serve as an intracellular elutable protein purification tag. The isc-p85alpha fusion protein could be specifically affinity-purified from the lysates of transfected Drosophila S2 cells with NP-sepharose and eluted with NIPcap, indicating the functional folding of the iscFv in the reducing environment of the cytosol. Furthermore, co-purification of the catalytic subunit of PI3K (p110) was achieved from lysates of co-transfected S2 cells as well as RBL-2H3 mast cells stably expressing isc-p85alpha. This indicates that the iscFv part of isc-p85alpha does not negatively influence p85alpha folding and interaction with p110. Moreover, successful incorporation of the p85alpha-moiety of isc-p85alpha into endogenous protein complexes in mast cells suggests the use of isc-containing fusion proteins for the native purification, elution, and analysis of intracellular signaling complexes.

Animals↗
PubMed1994

Macrogolgin--a new 376 kD Golgi complex outer membrane protein as target of antibodies in patients with rheumatic diseases and HIV infections.

Antibodies against the Golgi complex (GC) were found by indirect immunofluorescence microscopy in the serum of two patients with sclerodermia and Sjögren syndrome. Serum from one patient was used to screen clones from an oligo (dT) primed HeLa cDNA expression library. Four overlapping cross hybridizing clones (G1, G12, G13, G14) were found. One additional 5' clone (G15) was retrieved from a random primed lambda gt11 human thyroid cDNA library by nucleic acid hybridization, exploiting sequence information of clone G12. Additional clones for both the 5' and 3' ends were generated by RF-PCR from HeLa cell mRNA. Alignment of the overlapping clones resulted in a consensus cDNA of 10,300 bp encoding a protein of 376 kD. A corresponding mRNA of about 10 kb was found in Northern blots of RNA from various cultured cells. The most distinct features of the protein were the extraordinarily high fraction of alpha-helical domains containing heptad repeats with the probability of forming coiled-coils and the structure similarities with the myosin family and the yeast intracellular transport protein USO1. Five overlapping cDNA fragments covering the entire open reading frame were used to synthesize recombinant proteins for affinity purification of the antibodies in the two patients' sera. By use of these affinity purified antibodies, staining of the GC of various cultured cell lines was reproduced. The antibody target was dissociated within 15 min after brefeldin A exposure of cultured cells, a phenomenon, which was fully reversible within 30 min after withdrawal of the drug. Sucrose step gradient separation of GC enriched microsomal fractions from rat liver showed a natural antigen of about 380 kD co-fractionating with the GC marker galactosyltransferase. KCl extraction, Triton X-114 partition, as well as trypsin digestion of microsomal fractions revealed that the hydrophilic protein has to be located on the cytoplasmatic surface of GC vesicles. Using the five blotted recombinant protein fragments, anti-GC antibodies were found in 18 of 164 (11%) HIV positive patients but in none of the 64 healthy controls. HIV patients as well as the two original patients showed a diverse antibody spectrum recognizing different epitopes of the recombinant proteins. The protein characterized herein, for which we propose the provisional name macrogolgin, constitutes the largest protein known so far associated with the GC.

Amino Acid Sequence↗
PubMed2005

Expression and purification of recombinant vascular endothelial-statin.

We have recently discovered VE-statin (egfl7), a novel protein specifically expressed by endothelial cells during mouse development and in the adult. VE-statin is expected to play an essential role during the formation of new blood vessels. Here, we have expressed the coding sequence for VE-statin in bacteria and designed a protocol for the production and purification of large amounts of the protein. The protocol is based on an affinity purification step followed by a strong cation-exchange chromatography and a refolding procedure adapted to epidermal growth factor domains and also to the high tendency of the protein to precipitate in concentrated solutions. The purified protein is pure as assessed by SDS-PAGE, immunoblot and mass spectrometry, and is biologically active as a repressor of human aortic smooth muscle cell migration induced by platelet-derived growth factor-BB.

Amino Acid Sequence↗
PubMed1995

Human anti-Ro autoantibodies bind peptides accessible to the surface of the native Ro autoantigen.

The relationship between fine specificity of linear epitopes and conformational determinants has been explored in a naturally arising human autoimmune response. In particular, the hypothesis tested is that the linear epitopes of the human Ro autoantigen are components of its conformational epitopes. Twenty groups among the 531 overlapping octapeptides 60 kDa Ro are variably bound by anti-Ro precipitin positive lupus sera whose reactivity was easily distinguished from sera of normal controls and of anti-Ro precipitin negative lupus patients. The specific activities of anti-peptide antibodies and of anti-native Ro autoantibodies are similarly increased after affinity enrichment using native human Ro as ligand. Moreover, affinity-enriched anti-native Ro autoantibodies bind virtually the same 20 groups of epitopes recognized by whole anti-Ro positive sera. Two peptides (residues 274-290 and 480-494) from the defined 60 kDa Ro octapeptide epitopes have been prepared and used as ligands for affinity purification of peptide specific autoantibodies. The binding of both whole IgG and affinity-enriched peptide specific autoantibodies is inhibited by native Ro autoantigen. Thus, none of the available data can be construed to support the existence of cryptic linear epitopes in this system. Indeed, the data are only consistent with the conclusion that all of the anti-Ro octapeptide autoantibodies are part of the population of anti-native Ro autoantibodies in this naturally arising autoimmune response.

Amino Acid Sequence↗
PubMed1992

Expression and assembly of a functional E1 component (alpha 2 beta 2) of mammalian branched-chain alpha-ketoacid dehydrogenase complex in Escherichia coli.

We have expressed an active recombinant E1 decarboxylase component of the mammalian branched-chain alpha-ketoacid dehydrogenase complex in Escherichia coli by subcloning mature E1 alpha and E1 beta subunit cDNA sequences into a bacterial expression vector. To permit affinity purification under native conditions, the mature E1 alpha subunit was fused with the affinity ligand E. coli maltose-binding protein (MBP) through an endoprotease Factor Xa-specific linker peptide. When co-expressed, the MBP-E1 alpha fusion and E1 beta subunits were shown to co-purify as a MBP-E1 component that exhibited both E1 activity and binding competence for recombinant branched-chain E2 component. In contrast, in vitro mixing of individually expressed MBP-E1 alpha and E1 beta did not result in assembly or produce E1 activity. Following proteolytic removal of the affinity ligand and linker peptide with Factor Xa, a recombinant E1 species was eluted from a Sephacryl S-300HR sizing column as an enzymatically active 160-kDa species. The latter showed 1:1 subunit stoichiometry, which was consistent with an alpha 2 beta 2 structure. The recovery of this 160-kDa recombinant E1 species (estimated at 0.07% of total lysate protein) was low, with the majority of the recombinant protein lost as insoluble aggregates. Our findings suggest that the concurrent expression of both E1 alpha and E1 beta subunits in the same cellular compartment is important for assembly of both subunits into a functional E1 alpha 2 beta 2 heterotetramer. By using this co-expression system, we also find that the E1 alpha missense mutation (Tyr-393----Asn) characterized in Mennonites with maple syrup urine disease prevents the assembly of soluble E1 heterotetramers.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1998

Preclinical characterization and in vivo imaging studies of an engineered recombinant technetium-99m-labeled metallothionein-containing anti-carcinoembryonic antigen single-chain antibody.

UNLABELLED: We describe the engineering of a novel single-chain fragment (scFv) metallothionein (MET) containing anti-carcinoembryonic antigen (CEA) antibody (referred to as MET-scFv) for use as a diagnostic imaging agent in colorectal cancer. METHODS: Site-directed cloning of annealed oligonucleotides, containing both the MET and a c-myc tag sequence, into a pUC19-based expression vector enabled soluble secreted protein expression from Escherichia coli. Affinity purification was used to purify the protein using an anti-c-myc affinity column. The specificity of both the unlabeled and labeled MET-scFv for CEA was demonstrated by solid-phase enzyme-linked immunosorbent assay and radioimmunoassay and by fluorescence-activated cell sorting analysis on CEA-expressing human colorectal LS-174T cells. Technetium-99m labeling was achieved using a Zn2+ transchelation step, enabling direct 99mTc transfer without separate reduction of MET. In vitro stability was demonstrated by fast protein liquid chromatography analysis of labeled MET-scFv, incubated with bovine serum albumin (BSA), transferrin and mouse serum. Last, in vivo pharmacokinetics, biodistribution and imaging were performed. RESULTS: Yields of 6 mg/liter induced culture purified protein were achieved. Successful site-specific labeling was demonstrated using a Zn2+ transchelation modification of a pretinning method, which also enabled lower amounts of the reducing agent to be used. The specificity for CEA was retained after labeling. Despite a rapid serum clearance (t(1/2alpha) = 2.8 min), adequate localization to tumor of 5.37% injected dose/g at 4 hr was demonstrated. Moreover, the short-lived t(1/2alpha) of scFv, its early tumor targeting and rapid blood-pool clearance gave tumor-to-blood ratios of 2.07 by 4 hr, enabling early gamma camera imaging. Successful and specific imaging was achieved using LS-174T xenografts in nude mice by 3-6 hr. CONCLUSION: A recombinant MET containing scFv was successfully expressed, purified and labeled with 99Tc. The stable site-specific labeling of 99Tc, combined with the rapid plasma clearance of the scFv, led to successful early in vivo imaging of xenografted mice.

Animals↗
PubMed2003

Isolation of antigens and antibodies by affinity chromatography.

Antibody-antigen binding constants are commonly strong enough for an effective affinity purification of antibodies (by immobilized antigens) or antigens (by immobilized antibodies) to work out a straightforward purification method. A drawback is that antibodies are large protein molecules and subject to denaturation under conditions required for the elution from the complex. Structures of antigens can vary but usually antigens are also equally subject to similar problems. The lability of the components can sometimes make the procedure sophisticated, but usually in all cases it is possible to find a satisfactory approach. In certain cases, specific interactions of the Fc part of antibodies are more facile to exploit for their purification.

Antibodies↗
PubMed1994

Complementary peptides as antibody mimetics for protein purification and assay.

The possibility of designing sequence-directed recognition peptides (complementary peptides) able to noncovalently associate target peptides or proteins is one of the most important biotechnological applications deriving from the molecular recognition theory [MRT]. Complementary peptides can be used widely as synthetic ligands for the development of affinity purification strategies to isolate target peptides or proteins from crude sources. Generally, the observed affinity and selectivity are sufficient to allow one-step purification of target molecules directly from crude mixtures and the possibility of producing the ligands in enzymatically stable forms greatly enhance their applicability. In addition, the noninterference of nonionic detergents or denaturants on recognition expand their use in the case of poorly soluble targets. The ligand's synthetic nature overcomes all the problems associated with the use of immunoaffinity columns, since the possibility of biological contaminations is extremely limited. Numerous examples demonstrate the usefulness of this methodology, which allows the creation of a large number of peptidyl ligands tailored to specific purification needs. Recognition properties of complementary peptides can be applied also to the development of solid-phase assays for the identification and quantification of different molecular targets. As antibody mimetics, they can be used on solid phases to capture, and then to detect and consequently quantify, the desired target polypeptide in complex biological mixtures. Even if assay sensitivity cannot be compared with conventional antibody-based assays, the simplicity of complementary peptide design and production makes their use an attractive alternative in various circumstances.

Amino Acid Sequence↗