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Biomedical subjects

E Nice

Publications and source records attributed to E Nice.

22 records · Page 2Linked to original sources

Electrophoretic analysis of the novel antigen for the gastrointestinal-specific monoclonal antibody, A33.

The murine monoclonal antibody A33 (mAbA33) recognises a human cell membrane-associated antigen selectively expressed in epithelial cells of the lower gastrointestinal tract and > 90% of colonic cancers, but is not detected in a wide range of other normal tissues by immunohistochemical analysis. In phase I/II clinical triasl, mAbA33 has been shown to target advanced colon cancers and the humanized version is currently being evaluated in therapy studies. Although the mAbA33 has been well characterised by immunohistochemical and clinical studies, until recently, the target antigen has remained poorly defined. This was largely attributable to the antigenic determinant recognised by mAbA33 being dependent on the native spatial conformation of the A33 antigen which impeded its identification by conventional two-dimensional electrophoresis (2-DE) and immunoblot analysis. We have developed an immunoblot method, based on nonreducing/non-urea precast 2-DE gels, that has facilitated the purification of the detergent (0.3% Triton X-100) solubilised A33 antigen from the human colon cancer cell lines LIM1215 and SW1222. Under these 2-DE conditions, the A33 antigen electrophoreses with an apparent M(r) approximately 41000 and pI 5.0-6.0. Attempts to isolate the A33 antigen from 2-DE gels for direct structural analysis were unsuccessful, due to its co-electrophoresis with actin and cytokeratin proteins. However, using Western blot and biosensor detection the A33 antigen has been purified chromatographically and N-terminal sequence analysis was possible. Using polyclonal antibodies raised against a synthetic peptide corresponding to the N-terminal region of the A33 antigen we have used Western blot analysis to localise the molecule in our master 2-DE protein database for normal human colon crypts and several colon carcinoma cell lines (URL address: http:(/)/www.ludwig.edu.au). Under reducing 2-DE conditions, the A33 antigen electrophoresis as 6 differentially charged isoforms (pI 4.6-4.8) with a single molecular weight species at M(r) approximately 55000.

3T3 Cells↗

Biosensor-based micro-affinity purification for the proteomic analysis of protein complexes.

A biosensor-based micro-affinity purification method to recover protein binding partners and their complexes for down stream proteomics analysis has been developed using the BIAcore 3000 fitted with a prototype Surface Prep Unit (SPU). The recombinant GST-intracellular domain of E-cadherin or the recombinant GST-beta-catenin binding domain of Adenomatous Polyposis Coli (APC) were immobilized onto the SPU and used to affinity purify binding partners from chromatographically enriched SW480 colon cancer cell lysates. A GST- immobilized surface was used as a control. Samples recovered from the SPU were subjected to SDS-PAGE with sensitive Coomassie staining followed by automated in-gel digestion and LC-MS/MS. The results obtained using the SPU were compared with similar experiments performed using Sepharose beads.

Biosensing Techniques↗

Equilibrium analysis of the interaction between a synthetic peptide of influenza virus hemagglutinin and monoclonal antibodies.

The affinity of interaction between two monoclonal antibodies and a synthetic peptide representing the C-terminal 23 residues of the heavy chain (HA1) of influenza virus hemagglutinin were determined using an air-driven ultracentrifuge. The technique makes use of common laboratory equipment and is based on sound theoretical principles. Because the method does not rely on the solid-phase immobilisation of one of the interacting species, it circumvents problems associated with ELISA-like assays, which, in the case of peptides, may involve the immobilisation of ligand through association of amino acid residues necessary for recognition by antibody. The technique should be applicable to the study of a wide range of ligand-acceptor systems. Because only one of the reagents needs to be pure to allow labelling, prior purification of the biological receptor is not necessary. The method also lends itself to inhibition experiments in which the effects of various homologs on the binding event can be examined in a way which permits an evaluation of potential agonists and antagonists.

Antibodies, Monoclonal↗