The present disclosure relates to, inter alia, a method of quantitating an amount of an antibody molecule from a mixture comprising two or more antibody molecules, comprising separating each of the two or more antibody molecules from the mixture by hydrophobic interaction chromatography high performance liquid chromatography (HIC-HPLC) and quantitating an amount of each antibody molecule, wherein the molecular weight of each antibody molecule is within 15 kDa of any other antibody molecule in the mixture and either each antibody molecule is different from another antibody molecule in the mixture by more than about 0.25 unit on the Kyte & Doolittle hydropathy scale or each of the antibody molecules when run alone on HIC-HPLC elutes at distinct run time with little overlap from the other antibody molecules in the mixture, or both.

The present disclosure relates to, inter alia, a method of quantitating an amount of an antibody molecule from a mixture comprising two or more antibody molecules, comprising separating each of the two or more antibody molecules from the mixture by hydrophobic interaction chromatography high performance liquid chromatography (HIC-HPLC) and quantitating an amount of each antibody molecule, wherein the molecular weight of each antibody molecule is within 15 kDa of any other antibody molecule in the mixture and either each antibody molecule is different from another antibody molecule in the mixture by more than about 0.25 unit on the Kyte & Doolittle hydropathy scale or each of the antibody molecules when run alone on HIC-HPLC elutes at distinct run time with little overlap from the other antibody molecules in the mixture, or both.

Described herein are anchor-modified immunoglobulin polypeptides, wherein the anchor moors the immunoglobulin polypeptide to a receptor of interest. The anchor-modified immunoglobulin polypeptides are generally characterized at the N-terminus with an anchor, e.g., the receptor binding portion of a ligand that binds a receptor. Non-human animals genetically modified with recombinant immunoglobulin segments that encode the anchor-modified immunoglobulin polypeptides are capable of making the anchor-modified immunoglobulin polypeptides. Such non-human animals also provided, along with methods and compositions for making and using the non-human animals. Methods for producing anchor-modified immunoglobulins from non-human animals are also provided, as well as anchor-modified immunoglobulins generated therefrom.

A method is provided for purifying physiologically active proteins, especially antibodies, in order to remove impurities such as DNA contaminants and viruses with minimal loss of physiologically active proteins. The physiologically active protein is introduced into an aqueous solution of low conductivity at a pH of below the isoelectric point of the physiologically active protein to precipitate impurities as particles. The particles are removed, leaving a purified physiologically active protein.

In certain embodiments, the present invention provides novel antibody purification methods and systems using a potentially simple and cost-efficient means. In some embodiments, customized Z-33 derived from Staphylococcus aureus Protein A is used to construct immuno-amphiphile molecules which can assemble into immunofibers in aqueous solution with bioactive epitopes on the surface and have IgG binding ability.

The present invention is directed to a novel process for purifying a recombinant polypeptide from a solution comprising one or more impurities, wherein the process is a chromatography process which uses saccharin. The present invention also provides the use of saccharin in a process for purifying a recombinant polypeptide from a solution comprising one or more impurities, wherein the process is a chromatography process. The invention further provides a wash buffer for purifying using chromatography a recombinant polypeptide from a solution comprising one or more impurities, wherein the wash buffer comprises saccharin.

The invention encompasses the discovery that Fc-containing polypeptides that include branched glycans and that are sialylated on the branched glycan (e.g., on an α 1,3 and/or α 1,6 arm in the Fc region's N-linked glycosylation site), with, e.g., a NeuA-α 2,6-Gal or NeuAc-α 2,3-Gal terminal linkage, are useful in treating neurodegeneration, e.g., in the treatment of neurodegenerative diseases such as Alzheimer's Disease. The present disclosure provides, in pert, methods for treating neurodegeneration or neurodegenerative diseases by administering compositions containing such Fc-containing polypeptides as well as methods for evaluating, identifying, and/or producing (e.g., manufacturing) such polypeptides for the treatment of neurodegeneration.

The invention encompasses the discovery that Fc-containing polypeptides that include branched glycans and that are sialylated on the branched glycan (e.g., on an α 1,3 and/or α 1,6 arm in the Fc region's N-linked glycosylation site), with, e.g., a NeuA-α 2,6-Gal or NeuAc-α 2,3-Gal terminal linkage, are useful in treating neurodegeneration, e.g., in the treatment of neurodegenerative diseases such as Alzheimer's Disease. The present disclosure provides, in pert, methods for treating neurodegeneration or neurodegenerative diseases by administering compositions containing such Fc-containing polypeptides as well as methods for evaluating, identifying, and/or producing (e.g., manufacturing) such polypeptides for the treatment of neurodegeneration.

Disclosed herein are, inter alia, methods and compositions useful for detecting and/or quantifying host cell proteins during the production of a product, e.g., a recombinant protein, e.g., an antibody.

The present disclosure relates to methods of modifying the isoelectric point of an antibody. The method includes providing an antibody comprising a first polypeptide comprising a heavy chain variable region and a second polypeptide comprising heavy chain variable region and substituting, in at least one of the first and second polypeptides of the antibody, one or more amino acid residues of the heavy chain variable region (V.sub.H) at positions 7, 9, 11, 14, 41, 70, 74, 82a, 84, and 113, according to the Kabat numbering system, wherein the substituting increases or decreases the isoelectric point of the antibody.