Purification of butyrylcholinesterase using membrane adsorption

1. A method for making an enriched butyrylcholinesterase composition from a biological fluid having butyrylcholinesterase, the method comprising the steps of:

(A) contacting a biological fluid having butyrylcholinesterase with a fumed silica compound;

(B) adjusting the pH of the biological fluid contacted with the fumed silica compound in step (A) to a pH of from 4.15 to 4.35;

(C) filtering the pH adjusted biological fluid from step (B) to remove the fumed silica compound;

(D) applying the filtered biological fluid having butyrylcholinesterase from step (C) to a quaternary amine anion exchange material attached to a membrane equilibrated in with a buffer comprising acetate at a pH of from 4.15 to 4.35;

(E) washing the anion exchange material with a wash buffer comprising acetate;

(F) eluting butyrylcholinesterase from the anion exchange material by step elution with an elution buffer comprising acetate, thereby forming an enriched butyrylcholinesterase composition, wherein the butyrylcholinesterase content of the enriched butyrylcholinesterase composition is enriched at least 10 fold as compared to the starting biological fluid, as measured by butyrylcholinesterase activity per total protein; and

(G) enriching butyrylcholinesterase eluted from the anion exchange material in step (F) using a procainamide affinity purification material,

wherein the biological fluid in step (A) is a suspended Cohn Fraction IV.

2. The method of claim 1 , further comprising solvent-detergent treatment of the filtered biological fluid having butyrylcholinesterase from step (C), prior to step (D).

3. The method of claim 1 , wherein the total protein applied to the anion exchange membrane is at least 1000 mg per mL membrane volume.

4. The method of claim 1 , wherein the total protein applied to the anion exchange membrane is at least 2000 mg per mL membrane volume.

5. The method of claim 1 , wherein the butyrylcholinesterase content of the enriched butyrylcholinesterase composition is enriched at least 20 fold as compared to the starting biological fluid, as measured by butyrylcholinesterase activity per total protein.

6. The method of claim 1 , wherein the butyrylcholinesterase content of the enriched butyrylcholinesterase composition is enriched at least 40 fold as compared to the starting biological fluid, as measured by butyrylcholinesterase activity per total protein.

7. The method of claim 1 , wherein the butyrylcholinesterase content of the enriched butyrylcholinesterase composition is enriched at least 60 fold as compared to the starting biological fluid, as measured by butyrylcholinesterase activity per total protein.

8. The method of claim 1 , butyrylcholinesterase is applied to the anion exchange material attached to a membrane at a flow rate of at least 1.5 times membrane volume per minute.

9. The method of claim 1 , wherein the conductivity of the biological fluid applied to the anion exchange material attached to a membrane is 2.8 mS/cm or less.

10. The method of claim 1 , wherein the anion exchange material attached to a membrane is a Q membrane, and at least two Q membranes are connected in series.

11. The method of claim 1 , wherein the conductivity of the wash buffer in the washing step is 3.8 mS/cm or less.

12. The method of claim 1 , wherein the conductivity of the elution buffer in the eluting step is at least 5.6 mS/cm.

13. The method of claim 1 , wherein the membrane is in a series of two or more membranes.