Provided is a high-loading and alkali-resistant protein A magnetic bead. The magnetic bead can maintain chemical stability under pH 2-14 and has an immunoglobulin G (IgG) binding capacity greater than 50 mg/mL. Further provided is a method for purifying and/or detecting an immunoglobulin, comprising a step of contacting a sample containing the immunoglobulin with the high-loading and alkali-resistant protein A magnetic bead. The alkali-resistant protein A magnetic bead can realize rapid purification of immunoglobulin, saving about 80% of treatment time and reducing total purification costs by 50%. In addition, the alkali-resistant protein A magnetic bead has high alkali resistance. An alkaline method for in situ cleaning can be performed to regenerate the magnetic bead after use. The magnetic bead has rapid magnetic response and good dispersiveness, realizing rapid magnetic bead enrichment, cleaning, and elution. The magnetic bead facilitates automated, high-throughput, and large volume purification of a sample.

Provided is a high-loading and alkali-resistant protein A magnetic bead. The magnetic bead can maintain chemical stability under pH 2-14 and has an immunoglobulin G (IgG) binding capacity greater than 50 mg/mL. Further provided is a method for purifying and/or detecting an immunoglobulin, comprising a step of contacting a sample containing the immunoglobulin with the high-loading and alkali-resistant protein A magnetic bead. The alkali-resistant protein A magnetic bead can realize rapid purification of immunoglobulin, saving about 80% of treatment time and reducing total purification costs by 50%. In addition, the alkali-resistant protein A magnetic bead has high alkali resistance. An alkaline method for in situ cleaning can be performed to regenerate the magnetic bead after use. The magnetic bead has rapid magnetic response and good dispersiveness, realizing rapid magnetic bead enrichment, cleaning, and elution. The magnetic bead facilitates automated, high-throughput, and large volume purification of a sample.

This disclosure relates to methods for the prevention of the reduction of disulfide bonds in a polypeptide expressed in a recombinant host cell, comprising, following fermentation, adding selenite and/or its salts or derivatives to a harvest solution of the recombinant host cell, wherein the disulfide bond in the polypeptide remains non-reduced.

The present invention relates to a vitamin E-based amphipathic compound, a method for producing same, and a method for extracting, solubilizing, stabilizing, or crystallizing a membrane protein using same. By using a compound according to the present invention, not only is an excellent membrane protein extraction and solubilization effect achieved, but the membrane protein can be stably stored for a long period of time in an aqueous solution, and thus the compound can be utilized in analyzing the function and structure of the membrane protein. Moreover, the vitamin E-based amphipathic compounds exhibited superb properties in the visualization of protein compounds through an electron microscope. Membrane protein structure and function analysis is one of the fields of greatest interest in biology and chemistry today, and since at least half of new drugs currently being developed target membrane proteins, the vitamin E-based amphipathic compounds may be applied to the membrane protein structure research, which is closely related to the development of new drugs.

Spin columns that include a poly(acid) membrane separation matrix are provided. Also provided are kits that include the subject devices, as well as methods of using the devices, e.g., in sample preparation (such as protein purification) protocols.

Spin columns that include a poly(acid) membrane separation matrix are provided. Also provided are kits that include the subject devices, as well as methods of using the devices, e.g., in sample preparation (such as protein purification) protocols.

The invention provides methods of preparation of lipoproteins from a biological sample, including HDL, LDL, Lp(a), IDL, and VLDL, for diagnostic purposes utilizing differential charged particle mobility analysis methods. Further provided are methods for analyzing the size distribution of lipoproteins by differential charged particle mobility, which lipoproteins are prepared by methods of the invention. Further provided are methods for assessing lipid-related health risk, cardiovascular condition, risk of cardiovascular disease, and responsiveness to a therapeutic intervention, which methods utilize lipoprotein size distributions determined by methods of the invention.

The invention provides methods of preparation of lipoproteins from a biological sample, including HDL, LDL, Lp(a), IDL, and VLDL, for diagnostic purposes utilizing differential charged particle mobility analysis methods. Further provided are methods for analyzing the size distribution of lipoproteins by differential charged particle mobility, which lipoproteins are prepared by methods of the invention. Further provided are methods for assessing lipid-related health risk, cardiovascular condition, risk of cardiovascular disease, and responsiveness to a therapeutic intervention, which methods utilize lipoprotein size distributions determined by methods of the invention.

The invention provides an improved host strain for production of desired protein.

The invention provides an improved host strain for production of desired protein.