1. A method of purifying a protein expressed in a non-native soluble form in a non-mammalian expression system comprising: (a) lysing a non-mammalian cell in which the protein is expressed in a non-native soluble form to generate a cell lysate; (b) contacting the cell lysate with a separation matrix under conditions suitable for the protein to associate with the separation matrix; (c) washing the separation matrix; and (d) eluting the protein from the separation matrix, wherein the separation matrix is an affinity resin selected from the group consisting of Protein A, Protein G and a synthetic mimetic affinity resin.

7. A method of purifying a protein expressed in a non-native limited solubility form in a non-mammalian expression system comprising: (a) expressing a protein in a non-native limited solubility form in a non-mammalian cell; (b) lysing a non-mammalian cell; (c) solubilizing the expressed protein in a solubilization solution comprising one or more of the following: (i) a denaturant; (ii) a reductant; and (iii) a surfactant; (d) forming a refold solution comprising the solubilization solution and a refold buffer, the refold buffer comprising one or more of the following: (i) a denaturant; (ii) an aggregation suppressor; (iii) a protein stabilizer; and (iv) a redox component; (e) directly applying the refold solution to a separation matrix under conditions suitable for the protein to associate with the matrix; (f) washing the separation matrix; and (g) eluting the protein from the separation matrix, wherein the separation matrix is a non-affinity resin selected from the group consisting of ion exchange, mixed mode, and a hydrophobic interaction resin.

1. A method of purifying a protein expressed in a non-native soluble form in a non-mammalian expression system comprising: (a) lysing a non-mammalian cell in which the protein is expressed in a nonnative soluble form to generate a cell lysate; (b) contacting the cell lysate with a separation matrix under conditions suitable for the protein to associate with the separation matrix; (c) washing the separation matrix; and (d) eluting the protein from the separation matrix.

9. A method of purifying a protein expressed in a non-native limited solubility form in a non-mammalian expression system comprising: (a) solubilizing the expressed protein in a solubilization solution comprising one or more of the following: (i) a denaturant; (ii) a reductant; and (iii) a surfactant; (b) forming a refold solution comprising the solubilization solution and a refold buffer, the refold buffer comprising one or more of the following: (i) a denaturant; (ii) an aggregation suppressor; (iii) a protein stabilizer; and (iv) a redox component; (c) applying the refold solution to a separation matrix under conditions suitable for the protein to associate with the matrix; (d) washing the separation matrix; and (e) eluting the protein from the separation matrix.

1. A method of refolding proteins expressed in a non-mammalian expression system, the method comprising: contacting the proteins with a preparation that supports the renaturation of at least one of the proteins to a biologically active form, to form a refold mixture, the preparation comprising: at least one ingredient selected from the group consisting of a denaturant, an aggregation suppressor and a protein stabilizer; an amount of oxidant; and an amount of reductant, wherein the amounts of the oxidant and the reductant are related through a thiol-pair ratio and a thiol-pair buffer strength, wherein the thiol-pair ratio is in the range of 0.001-100; and wherein the thiol-pair buffer strength maintains the solubility of the preparation; and incubating the refold mixture so that at least about 25% of the proteins are properly refolded.

10. A method of refolding proteins expressed in a non-mammalian expression system, the method comprising: contacting the proteins with a preparation that supports the renaturation of at least one of the proteins to a biologically active form, to form a refold mixture, the preparation comprising: at least one ingredient selected from the group consisting of a denaturant, an aggregation suppressor and a protein stabilizer; an amount of oxidant; and an amount of reductant, wherein the amounts of the oxidant and the reductant are related through a thiol-pair ratio and a thiol-pair buffer strength, wherein the thiol-pair ratio is in the range of 0.001-100; and wherein the thiol-pair buffer strength maintains the solubility of the preparation; and incubating the refold mixture so that about 30-80% of the proteins are properly refolded.

16. A method of refolding proteins expressed in a non-mammalian expression system, the method comprising: preparing a solution comprising: the proteins; at least one ingredient selected from the group consisting of a denaturant, an aggregation suppressor and a protein stabilizer; an amount of oxidant; and an amount of reductant, wherein the amounts of the oxidant and the reductant are related through a thiol-pair ratio and a thiol-pair buffer strength, wherein the thiol-pair ratio is in the range of 0.001-100, and wherein the thiol-pair buffer strength maintains the solubility of the solution; and incubating the solution so that at least about 25% of the proteins are properly refolded.

26. A method of refolding proteins expressed in a non-mammalian expression system, the method comprising: preparing a solution comprising: the proteins; at least one ingredient selected from the group consisting of a denaturant, an aggregation suppressor and a protein stabilizer; an amount of oxidant; and an amount of reductant, wherein the amounts of the oxidant and the reductant are related through a thiol-pair ratio and a thiol-pair buffer strength, wherein the thiol-pair ratio is in the range of 0.001-100, and wherein the thiol-pair buffer strength maintains the solubility of the solution; and incubating the solution so that about 30-80% of the proteins are properly refolded.