Method for purifying proteins

Abstract

The present invention provides methods and kits for purifying a target protein group. The method comprises the steps of contacting a sample comprising at least 95% of the target protein group and at most 5% of contaminating proteins with a library of binding moieties having different binding moieties, binding the contaminating proteins and a minority of the target protein group to the library of binding moieties, separating the unbound target protein group from the proteins bound to the library of binding moieties and collecting the unbound target protein. The collected target protein is more pure than the target protein group in the sample.

1 . A pharmaceutical composition comprising:
 (i) a target protein group prepared by
 (a) contacting a sample comprising at least 95% of the target protein group and at most 5% of contaminating proteins with a library comprising at least 100 different binding moieties in an amount sufficient to bind contaminating proteins and a minority of the target protein group; 
 (b) binding the contaminating proteins and the minority of the target protein group to the library of binding moieties; 
 (c) separating the unbound target protein group from the contaminating proteins and target protein group bound to the library of binding moieties; and 
 (d) collecting the unbound target protein group from the sample; 
   whereby the collected target protein group is more pure than the target protein group in the sample, and   (ii) a pharmaceutically acceptable carrier.   
     
     
         2 . The composition according to  claim 1 , comprising a target protein group selected from the group consisting of an enzyme, a hormone, a growth factor, a receptor, a vaccine, an immunoglobulin and fragments of any of the foregoing. 
     
     
         3 . The composition according to  claim 1 , comprising a target protein group selected from the group consisting of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), epidermal growth factor (EGF), transforming growth factor (TGF), insulin-like growth factor (IGF), erythropoietin (EPO), bone morphogenetic protein (BMP), bone-derived neurotrophic factor (BDNF), colony stimulating factor (CSF), nerve growth factor (NGF), human growth hormone (hGH), tumor necrosis factor (TNF), insulin, tissue-type plasminogen activator (t-PA), interferon, interleukin (IL) and herceptin. 
     
     
         4 . A kit for purifying a target protein group, the kit comprising:
 (i) a library of binding moieties having at least 100 different binding moieties; and   (ii) an instruction to purify the target protein group by contacting a sample comprising at least 95% of the target protein group and at most 5% of contaminating proteins with the library of binding moieties.   
     
     
         5 . The kit according to  claim 4 , further comprising:
 (iii) a plurality of containers retaining incubation buffers for contacting the sample with the library of binding moieties.   
     
     
         6 . The kit according to  claim 4 , further comprising:
 (iii) a fractionating column.