The invention herein provides a method for recovering a polypeptide comprising exposing a composition comprising a polypeptide to a reagent which binds to, or modifies, the polypeptide, wherein the reagent is immobilized on a solid phase; and then passing the composition through a filter bearing a charge which is opposite to the charge of the reagent in the composition, so as to remove leached reagent from the composition.
RELATED APPLICATION
This application is a non-provisional application filed under 37 CFR 1.53(b)(1), claiming priority under 35 USC 119(e) to provisional application number 60/050,951 filed Jun. 13, 1997, the contents of which are incorporated herein by reference.
A method for purifying a desired heterologous polypeptide from microbial fermentation broth or homogenate in which it is produced and solubilized is described. This method involves adding to the broth or homogenate an effective amount of a solution of 6,9-diamino-2-ethoxyacridine lactate (ethacridine lactate) to precipitate host cell impurities under conditions wherein the majority of polypeptide remains soluble, and separating the desired polypeptide from the broth or homogenate. The broth or homogenate containing the ethacridine lactate and polypeptide is also disclosed.
A method is provided for separating a protein from one or more other proteins using hydroxyapatite chromatography in which the protein does not bind to hydroxyapatite but the other protein(s) does. In some embodiments, a second protein affixed to a solid support has been used previously to purify the protein by affinity chromatography, and small amounts of the second protein are introduced in the sample during this process. The protein being purified can comprise at least one constant antibody immunoglobulin domain. The second protein can bind to proteins comprising such a domain.
A method for purifying a desired heterologous polypeptide from microbial fermentation broth or homogenate in which it is produced and solubilized is described. This method involves adding to the broth or homogenate an effective amount of a solution of 6,9-diamino-2-ethoxyacridine lactate (ethacridine lactate) to precipitate host cell impurities under conditions wherein the majority of polypeptide remains soluble, and separating the desired polypeptide from the broth or homogenate. The broth or homogenate containing the ethacridine lactate and polypeptide is also disclosed.
A method is provided for separating a protein from one or more other proteins using hydroxyapatite chromatography in which the protein does not bind to hydroxyapatite but the other protein(s) does. In some embodiments, a second protein affixed to a solid support has been used previously to purify the protein by affinity chromatography, and small amounts of the second protein are introduced in the sample during this process. The protein being purified can comprise at least one constant antibody immunoglobulin domain. The second protein can bind to proteins comprising such a domain.
The present invention provides a method for stabilizing a protein in a desired conformation by introducing at least one disulfide bond into the polypeptide. Computational design is used to identify positions where cysteine residues can be introduced to form a disulfide bond in only one protein conformation, and therefore lock the protein in a given conformation. Accordingly, antibody and small molecule therapeutics are selected that are specific for the desired protein conformation.The invention also provides modified integrin I-domain polypeptides that are stabilized in a desired conformation. The invention further provides screening assays and therapeutic methods utilizing the modified integrin I-domains of the invention.
