The University of British Columbia

Charles A Haynes

Anupam Singhal

Carl L G Hansen

John W Schrader

Daniel Jay Da Costa

Douglas G Kilburn

Pedro Aloise

Peter Tomme

Aimee Louise Creagh

There are provided methods, and devices for assaying for a binding interaction between a protein, such as a monoclonal antibody, produced by a cell, and a biomolecule. The method may include retaining the cell within a chamber having an aperture; exposing the protein produced by the cell to a capture substrate, wherein the capture substrate is in fluid communication with the protein produced by the cell and wherein the capture substrate is operable to bind the protein produced by the cell; flowing a fluid volume comprising the biomolecule through the chamber via said aperture, wherein the fluid volume is in fluid communication with the capture substrate; and determining a binding interaction between the protein produced by the cell and the biomolecule.

Methods for assaying cellular binding interactions

A compound having a polysaccharide binding domain such as contained by a cellulose and essentially lacking in polysaccharidase activity is purified from other ingredients in a mixture using an affinity partition system. A mixture containing the compound is contacted with a system containing as a first phase an aqueous solution of oligosaccharide polymer such as cellulose and as a second phase a solution of a polymer such as a poly(ethylene glycol)-poly(propylene glycol) copolymer. The compound petitions into the first phase and binds to the oligosaccharide polymer, preferably with a K,of 10,to 10,, to form a complex. The complex is collected, and the compound is dissociated from the oligosaccharide polymer. The compound may be formed of a non-peptide chemical moiety or a peptide moiety linked to a polypeptide having the polysaccharide binding domain. The compound may also be a fusion polypeptide containing the polysaccharide binding domain linked through a protease recognition sequence to a macromolecule such as an enzyme, a hormone or an antibody. The macromolecule can be removed by using a protease to cleave the recognition sequence. Another partition system contains the oligosaccharide polymer and a phase separation inducing agent such as a sulfate or citrate salt that induces separation to produce different phases.

Purification of a polypeptide compound having a polysaccharide binding domain by affinity phase separation

A two-phase partition system is provided for affinity separation of a composition containing a polysaccharide binding peptide from a mixture such as a fermentation broth. The peptide may be from an enzyme and lacking in polysaccharidase activity such as the binding domain of cellulase that binds to cellulose. The system contains a phase-forming oligosaccharide polymer such as a cellulose derivative to which the peptide binds with a Ka of 10.sup.3 M to 10.sup.7 M, and a phase inducing agent such as a polyethylene glycol polymer, or a salt present at sufficiently high concentration to induce phase separation. If the oligosaccharide polymer is thermoseparating, phase separation can be induced by heating. Using the system involves contacting a composition containing the peptide such as a fusion protein with the system, partitioning the composition into a phase containing the oligosaccharide polymer by binding to the polymer and recovering the polymer containing the bound composition. The peptide or a fusion protein containing the peptide can be contacted with a cell having a carbohydrate residue to which the peptide binds to form a complex, and the complex is separated with the system to produce a bound cell composition. The peptide may be linked through a protease recognition sequence to a macromolecule such as an enzyme, a hormone or an antibody, and the macromolecule can be removed by using a protease to cleave the recognition sequence.

Two-phase partition affinity separation system and affinity separated

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Charles A Haynes