Tetrameric N-terminally acetylated -synuclein is prepared by transforming an expression system with an expression vector encoding -synuclein, wherein the expression system expresses a native NatB acetylase complex or ortholog thereof and/or wherein an exogenous NatB acetylase complex or ortholog thereof is co-expressed in the expression system, inducing protein expression in the transformed expression system, lysing cells in the transformed expression system to produce a cell lysate, performing salt precipitation of the cell lysate, recovering tetrameric N-terminally acetylated -synuclein by centrifugation, and purifying the tetrameric N-terminally acetylated -synuclein. Compositions comprising the same and methods for identifying compounds that stabilize natively folded tetrameric -synuclein are also provided.

Provided herein is a novel method of purifying an IgG antibody from a preparation by use of an electropositive membrane having a defined porosity.

Systems and methods are described in which proteins are isolated from complex solutions in high yield and at high purity. Such systems and methods are carried out at ambient temperature and can be carried out at industrial scale with minimal energy requirements and minimal carbon footprint, using successive chromatographic separations that retain the protein or proteins of interest in flow-through fractions. At least one of the chromatography media used is selected to be capable of interacting with both contaminants and the protein of interest, however capacity of this media is selected such that the protein of interest is displaced and remains in the flow-through. Methods for isolation of IgG, albumin, and both IgG and albumin are provided.

Disclosed is a method for purifying a recombinant protein of interest from a recombinant cell expressing intracellularly the recombinant protein as an insoluble matter, comprising treating the recombinant cell under conditions where a protein derived from a host cell dissolves in a first aprotic polar solvent to which an inorganic salt is added or not but the recombinant protein does not dissolve, removing a first soluble fraction, and then treating the resulting first insoluble fraction under conditions where the recombinant protein dissolves in a second aprotic polar solvent to which an inorganic salt is added.

The invention is directed to a Ca2+ precipitable polypeptide tags and cassettes useful for purification of molecules from heterogeneous samples. The invention also relates to methods for bioseparation of molecules comprising Ca2+ precipitable tags and cassettes.

The present disclosure relates to a method for expressing, water-solubilizing, and purifying protein by using a calsequestrin-tag (CSQ-tag). Also provided are: a recombinant expression vector containing a CSQ-tag and a target protein; a host cell transformed using the recombinant expression vector; and a method for expressing and purifying a target protein by using a CSQ tag.

A method of purifying a desired protein from a preparation includes (a) providing the preparation in a form having less than about 5% of chromatin residing in an original production medium, (b) contacting the preparation with a nonionic organic polymer and a salt, a concentration of nonionic organic polymer being sufficient to precipitate the desired protein or cause its accretion on a hydrophilic surface, or maintain it in a precipitated state or accreted on the hydrophilic surface, the salt concentration being sufficient to produce greater than physiological conductivity, and (c) contacting the preparation with at least one electropositive surface, optionally in the presence of a salt concentration sufficient to produce greater than physiological conductivity, the desired protein does not substantially adsorb to the at least one electropositive surface while not preventing adsorption of acidic contaminants to the at least one electropositive surface.

Method of clarifying a crude protein solution, the method comprising to provide (100) a volume of the crude protein solution, mixing (101) Na.sub.2HPO.sub.4 and CaCl.sub.2) in water, forming a first solution, adding (102) the first solution to the volume of crude protein solution, thereby forming a second solution. NaCl is added to the first solution, the crude protein solution and/or to the second solution. The second solution is mixed (103). The thus formed flocculated material is separated (104) from the second solution, obtaining a clarified protein solution. The clarified protein solution may thereafter be purified by chromatography.

A method for the purification of a desired protein from a protein preparation includes conditioning the protein preparation by treatment with soluble organic multivalent ions, immobilized organic multivalent ions, or both, optionally in the presence of supersaturated allantoin, thereby removing at least 90% of chromatin, then (1) precipitating the desired protein with a nonionic organic polymer in the presence of non-protein-precipitating salts at greater than physiological concentration to provide a precipitate of the desired protein; or (2) precipitating the desired protein with a nonionic organic polymer in the absence of non-precipitating salts at greater than physiological concentration to provide a precipitate and subsequently washing the precipitate with a nonionic organic polymer in the presence of non-protein-precipitating salts at greater than physiological concentration.

The present disclosure relates to a method of producing collagen from an animal and more particularly, the present invention relates to a method for producing collagen by applying an acid and metal fluoride combination to an animal skin.