Methods of preventing and removing trisulfide bonds
The present invention pertains to methods of preventing and eliminating trisulfide bonds in proteins such as antibodies. In one embodiment, trisulfide bonds in proteins are converted to disulfide bonds as part of chromatographic purification procedures. In another embodiment, the formation of trisulfide bonds in proteins is inhibited by implementation of methods described herein during the cell culture production of such proteins. In another embodiment, monoclonal antibodies are produced by the methods described herein.
1. A cell culture for reducing the formation of trisulfide bonds in a protein comprising a culture medium which comprises an effective amount of an inhibitor of cysteine degradation selected from methyl pyruvate, ethyl pyruvate, glyceraldehyde, and glyoxylic acid.
2. The cell culture of claim 1 , further comprising a cell which expresses said protein.
3. The cell culture of claim 2 , wherein said cell is a mammalian cell.
4. The cell culture of claim 3 , wherein said mammalian cell is a CHO (Chinese Hamster Ovary) (including CHO-K1, CHO DG44, and CHO DUXB11), VERO, HeLa, (human cervical carcinoma), CVI (monkey kidney line), (including COS and COS-7), BHK (baby hamster kidney), MDCK, C127, PC12, HEK-293 (including HEK-293T and HEK-293E), PER C6, NSO, WI38, R1610 (Chinese hamster fibroblast) BALBC/3T3 (mouse fibroblast), HAK (hamster kidney line), SP2/0 (mouse myeloma), P3x63-Ag3.653 (mouse myeloma), BFA-1c1BPT (bovine endothelial cells), RAJI (human lymphocyte) or 293 (human kidney) cell.
5. The cell culture of claim 1 , wherein the ratio of the inhibitor to cysteine is about 5:1 to 1:10.
6. The cell culture of claim 1 , wherein said inhibitor is at a concentration of between about 50 μM to about 500 mM.
7. The cell culture of claim 6 , wherein said inhibitor is at a concentration of between about 100 μM to about 100 mM.
8. The cell culture of claim 7 , wherein said inhibitor is at a concentration of between about 1 mM and 100 mM.
9. The cell culture of claim 8 , wherein said inhibitor is at a concentration of between about 5 mM to about 50 mM.
10. The cell culture of claim 1 , wherein said culture medium comprises IMDM or DMEM.