Method for the production of domain antibodies

1. A method for promoting the formation of an intramolecular disulfide bridge in a domain antibody produced in yeast by fermentation in a culture medium, said method comprising:

exposing the domain antibody to oxidizing conditions by adding oxidizing metal ions to the culture medium during the culturing of the yeast, to the culture medium during the production phase of the domain antibody, to the culture medium after fermentation, to a supernatant comprising the domain antibody after removal of the yeast, and/or to a partially or highly purified preparation comprising the domain antibody, wherein the oxidizing metal ions are added to a final concentration of 0.15 to 10 mM; and

applying conditions that remove domain antibodies lacking at least one intramolecular disulfide bridge, wherein the conditions that remove domain antibodies lacking at least one intramolecular disulfide bridge are selected from:

a) binding domain antibodies comprising free thiol groups to suitable reactive groups, including but not limited to immobilized thiol groups; and

b) reverse phase high performance chromatography.

2. The method of claim 1 , wherein the oxidizing metal ions are added to a purified preparation comprising the domain antibody.

3. The method according to claim 1 , further comprising:

a) enhancing expression of a thiol isomerase in the yeast;

b) adapting the culturing conditions by one or more selected from the following: lowering culturing temperature and/or optimizing the culturing medium, by reduction of methanol feed for yeast requiring a methanol feed, lowering conductivity of the culture medium, addition of yeast extract and/or peptone, and any combination thereof;

c) refolding the domain antibody in the presence of a redox-buffer;

d) treating the domain antibody by oxygenation, increasing temperature, increasing pH, or high pressure, or any combination thereof; or

e) combinations of any of a) through d).

4. The method according to claim 3 , wherein the domain antibody is attached to a stationary phase of a chromatographic column.

5. The method according to claim 1 , wherein said yeast is Pichia, Hansenula, Saccharomyces, Kluyveromyces, Candida, Torulopsis, Torulaspora, Schizosaccharomyces, Citeromyces, Pachysolen, Debaromyces, Metschunikowia, Rhodosporidium, Leucosporidium, Botryoascus, Sporidiobolus , or Endomycopsis.

6. The method according to claim 1 , wherein the domain antibody is a light chain variable domain sequence or a heavy chain variable domain sequence.

7. The method according to claim 6 , wherein the domain antibody is a heavy chain variable domain sequence that is derived from a conventional four-chain antibody or that essentially consists of a heavy chain variable domain sequence that is derived from a heavy chain antibody.

8. The method according to claim 7 , wherein the domain antibody is a single domain antibody, a dAb or a Nanobody, or a VHH sequence.

9. The method of claim 1 , wherein the oxidizing metal ions comprise Cu2+, Fe2+, Fe3+, Zn2+, or a combination thereof.

10. A method for promoting the formation of an intramolecular disulfide bridge in a domain antibody produced in yeast by fermentation in a culture medium, said method comprising exposing the domain antibody to oxidizing conditions by: adding oxidizing metal ions to the culture medium during the culturing of the yeast, to the culture medium during the production phase of the domain antibody, to the culture medium after fermentation, and/or to a supernatant comprising the domain antibody after removal of the yeast, wherein the oxidizing metal ions are added to a final concentration of 0.15 to 10 mM; and/or adding oxidizing metal ions to a partially or highly purified preparation comprising the domain antibody;

wherein the method further comprises:

a) enhancing expression of a thiol isomerase in the yeast, wherein the thiol isomerase is selected from protein disulfide isomerase (PDI), calsequestrin, ERp72, ERp57, ERp60, ERp44, ERp5, ERp27 and PDIR;

b) adapting the culturing conditions by one or more selected from the following: lowering the culturing temperature by 5° C. as compared to the standard culturing temperature for the yeast; reducing the methanol feed by 30-80% as compared to the standard methanol feed for the yeast; lowering the conductivity of the culture medium by 30%-80% as compared to the standard medium for the yeast; adding yeast extract and/or peptone to the culture medium at a concentration in the feed of 0-20%; and any combination thereof;

c) refolding the domain antibody in the presence of a denaturant and a redox-buffer using 2M guanidinium hydrochloride and 1:5 mM/mM cystamine/cysteamine;

d) treating the domain antibody by increasing the temperature to 40-60° C., increasing pH to pH 8-9, and/or applying high pressure to 250-5000 bar; or

e) combinations of any of a) through d).

11. The method according to claim 10 , comprising enhancing expression of a thiol isomerase in the yeast, wherein said thiol isomerase is selected from protein disulphide isomerase (PDI), calsequestrin, ERp72, ERp57, ERp60, ERp44, ERp5, ERp27 and PDIR.

12. The method according to claim 10 , comprising lowering the culturing temperature by 5° C. as compared to the standard culturing temperature for the yeast.

13. The method according to claim 10 , comprising reducing the methanol feed by 30-80% as compared to the standard methanol feed for the yeast.

14. The method according to claim 10 , comprising lowering the conductivity of the culture medium by 30%-80% as compared to the standard medium for the yeast.

15. The method according to claim 10 , comprising adding yeast extract and/or peptone to the culture medium at a concentration in the feed of 0-20%.

16. The method according to claim 10 , comprising refolding the domain antibody in the presence of a denaturant and a redox-buffer using 2M guanidinium hydrochloride and 1:5 mM/mM cystamine/cysteamine.

17. The method according to claim 10 , comprising treating the domain antibody by increasing the temperature to 40-60° C., increasing pH to pH 8-9, and/or applying high pressure to 250-5000 bar.