PURIFICATION OF RECOMBINANTLY PRODUCED INTERFERON

1 - 29 . (canceled)

30 . A method of separating the oxidized monomeric isofonn of an interferon (IFN) from one or more undesired isoforms of that IFN in a mixture of recombinantly produced isoforms of the IFN, the method comprising:

(a) providing the mixture of 1FN isoforms in a first buffer solution;

(b) providing a chromatography column that is greater than 15 cm in length and packed with an anion exchange resin that is equilibrated with the first or a second buffer solution;

(c) loading the buffered IFN solution onto the anion exchange column;

(d) washing the loaded column with a wash solution;

(e) applying to the washed column a strong elution solution in an amount that is 1 to 10 bed volumes of the column, wherein the strong elution solution comprises a first phosphate concentration of 10 to 30 mM and has a pH of 5.4 to 6.6;

(f) applying to the column from step (e) a weak elution solution in an amount that is 2 to 20 bed volumes of the column, wherein the weak elution solution comprises a second phosphate concentration that is less than the first phosphate concentration and has a pH of 5.4 to 6.6; and

(g) collecting a plurality of eluate fractions that contain the oxidized IFN monomeric isoform.

31 . The method of claim 30 , wherein the anion exchange resin is a diethylaminoethyl anion exchange resin.

32 . The method of claim 31 , wherein the anion exchange resin is DEAE Sepharose Fast Flow.

33 . The method of any of claims 32 , wherein the IFN is a Type I IFN.

34 . The method of claim 33 , wherein the IFN is an interferon alpha (IFN-α).

35 . The method of claim 34 , wherein the IFN is an IFN-α2 and each of the first and second buffer solutions consists essentially of 10 mM Tris, 0-40 mM NaCI and has a pH of 7.0 to 8.5.

36 . The method of claim 35 , wherein the first buffer solution consists essentially of 10 mM Tris, 40 mM NaC1 and has a pH of 8.0, the second buffer solution consists essentially of 10 mM Tris and has a pH of 8.0, the wash solution consists essentially of 10 mM Tris and 14 mM NaC1 and has a pH of 8.0, the first phosphate concentration is about 17.5 mM and the second phosphate concentration is about 5 mM to about 7 mM, and each of the strong and weak elution solutions has a pH of 5.85.

37 . The method of claim 36 , wherein the IFN is an IFN-α2, the strong elution solution consists essentially of 17.5 mM sodium phosphate and the weak elution solution consists essentially of 5 mM sodium phosphate

38 . The method of claim 30 , wherein each of steps (c), (d), (e) and (f) is performed at a flow rate of 0.5 to 2.5 cm/min.

39 . The method of claim 30 , wherein each of steps (c) and (d) are performed at a flow rate of 2 cm/min and each of steps (e) and (0 are performed at a flow rate of 1 cm/min, the IFN is IFN-α2b, and the concentration of IFN-α2b isoform 1 in the IFN solution is between about 1.75 mg/ml and about 5.25 mg/ml.

40 . The method of claim 39 , wherein the concentration of IFN-α2b isoform 1 in the IFN solution is about 3.5 mg/ml, the amount of the strong elution solution applied in step (e) is 6 bed volumes and the amount of the weak solution applied in step (1) is 15 bed volumes.

41 . The method of claim 30 , wherein the volume of each of the eluate fractions collected in step (g) is about 20% of the bed volume.

42 . The method of claim 30 , wherein the IFN is IFN-α2b produced in a recombinant bacteria and from about 3% to about 20% of the isoforms in the IFN solution comprise IFN-α2b isoform 4.

43 . A method of separating isoform 1 of interferon alpha-2b (IFN-α2b) from isoform 4 of IFN-α2b in a mixture of recombinantly produced isoforms of IFN-α2b, the method comprising:

(a) providing a diethylaminoethyl (DEAE) anion exchange chromatography column that is at least about 20 cm in length and equilibrated with a buffer solution which consists essentially of 10 mM Tris and a pH of 8.0;

(b) loading the IFN-α2b mixture onto the DEAE column in a loading buffer that consists essentially of 10 mM Tris, 40 mM NaCI, and has a pH of from 7.5 to 8.0, wherein the IFN-α2b mixture is loaded at a flow rate of 2 cm per minute;

(c) washing the loaded column with 3 bed volumes of a wash solution at a flow rate of 2 cm per minute, wherein the wash solution consists essentially of 10 mM Tris HCI and 13 mM NaCI, and has a pH of 8.0;

(d) applying to the washed column 6 bed volumes of a strong elution solution at a flow rate of 1 cm per minute, wherein the strong elution solution consists essentially of 17.5 mM sodium phosphate and has a pH of 5.85;

(e) applying to the column from step (d) 15 bed volumes of a weak elution solution at a flow rate of 1 cm per minute, wherein the weak elution solution consists essentially of 5 mM sodium phosphate and has a pH of 5.85; and

(f) collecting a plurality of eluate fractions that contain isoform 1.

44 . The method of claim 43 , further comprising combining the collected eluate fractions in which the amount of isoform 4 is less than a desired purity criteria.

45 . The method of claim 44 , wherein the volume of each of the fractions collected in step (f) is about 20% of the bed volume.

46 . A method of separating a desired isoform of an interferon (IFN) from one or more undesired isoforms of that IFN in a mixture of recombinantly produced isoforms of the IFN, the method comprising:

(a) providing a chromatography column that is at least about 20 cm in length and packed with a diethylaminoethyl anion exchange resin that is equilibrated with a buffer solution, wherein the buffer solution consists essentially of about 10 mM Tris and a pH of about 8.0;

(b) applying the IFN isoform mixture to the anion exchange column in a loading solution of about 10 mM Tris and about 40 mM NaCl and which has a pH of about 8.0;

(c) washing the column from step (b) with about 3 bed volumes of a wash solution, wherein the wash solution consists essentially of about 10 mM Tris HC1 and about 13 mM NaCl, and has a pH of about 8.0;

(d) applying to the washed column about 6 bed volumes of a strong elution solution at a flow rate of 0.5 to 2.5 cm/min, wherein the strong elution solution has a first phosphate concentration of 15 to 25 mM and a pH of between 5.7 and 6.1;

(e) applying to the column from step (d) about 15 bed volumes of a weak elution solution at a flow rate of 0.5 to 2.5 cm/min, wherein the weak elution solution has a second phosphate concentration that is less than the first phosphate concentration and has a pH of between 5.7 and 6.1; and

(f) collecting a plurality of eluate fractions that contain the desired IFN isoform; and

(g) combining the collected eluate fractions in which the amount of the undesired IFN isoforms is less than a desired purity criteria.

47 . The method of claim 46 , wherein the desired isoform is the oxidized monomeric isoform of the IFN and wherein each of steps (b) and (c) are performed at a flow rate of 2 cm per minute.

48 . The method of claim 47 , wherein each of steps (d) and (e) are performed at a flow rate of 1 cm/min, the IFN is an IFN-α2, the concentration of IFN-α2 in the ITN solution is between about 1.75 mg/ml and about 5.25 mg/ml, the strong elution solution consists essentially of 17 mM sodium phosphate and has a pH of 5.85, and the weak elution solution consists essentially of 5 mM sodium phosphate and has a pH of 5.85.

49 . The method of claim 48 , wherein the IFN is IFN-α2b produced in a recombinant bacteria.