Method for protecting thiol group of protein
A method for protecting a thiol group in a protein having a free cysteine residue, which comprises adding a compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein.
1 . A method for protecting a thiol group in a protein having a free cysteine residue, which comprises adding a compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein.
2 . A method for inhibiting a polymerization reaction of proteins via thiol groups, which comprises protecting a thiol group in a protein having a free cysteine residue by adding a compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein.
3 . A method for inhibiting modification of a protein, which comprises protecting a thiol group in a protein having a free cysteine residue by adding a compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein.
4 . A method for inhibiting an exchange reaction of a thiol group in a protein with a disulfide bond formed in the molecule or between the molecules of the protein, which comprises protecting a thiol group in a protein having a free cysteine residue by adding a compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein.
5 . The method according to claim 1 , wherein the compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein is cystine, homocystine, lipoic acid or oxidized glutathione.
6 . The method according to claim 1 , wherein the compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein is cystine.
7 . A method for protecting a thiol group in a protein having a free cysteine residue, which comprises adding a compound which has a disulfide bond in the molecule and exerts substantially no influence on the activity of the protein simultaneously or separately from a compound which has a thiol group in the molecule and exerts substantially no influence on the activity of the protein.
8 . The method according to claim 7 , wherein the compound which has a thiol group in the molecule and exerts substantially no influence on the activity of the protein is cysteine, homocysteine, glutathione or dihydrolipoic acid.
9 . The method according to claim 7 , wherein the compound which has a thiol group in the molecule and exerts substantially no influence on the activity of the protein is cysteine.
10 . The method according to claim 1 , wherein the protein is a recombinant protein.
11 . The method according to claim 1 , wherein the protein is an antibody.
12 . The method according to claim 11 , wherein the antibody is an F(ab′) 2 antibody.
13 . The method according to claim 11 , wherein the antibody is a monoclonal antibody.
14 . The method according to claim 13 , wherein the monoclonal antibody has a thiol group in its variable region.
15 . The method according to claim 13 , wherein the monoclonal antibody has a free cysteine residue in its variable region.
16 . The method according to claim 13 , wherein the monoclonal antibody comprises the amino acid sequences represented by SEQ ID NOs:1, 2 and 3 in the Sequence Listing in its heavy chain hypervariable region, and the amino acid sequences represented by SEQ ID NOs:4, 5 and 6 in the Sequence Listing in its light chain hypervariable region.
17 . The method according to claim 13 , wherein the monoclonal antibody comprises a heavy chain variable region comprising the amino acid sequence represented by SEQ ID NO:7 in the Sequence Listing and a light chain variable region containing the amino acid sequence represented by SEQ ID NO:8 in the Sequence Listing.
18 . The method according to claim 1 , wherein the protein is produced by using a cell cultured in a serum-free medium.
19 . A protein which is obtainable by the method according to claim 18 .
20 . A pharmaceutical composition which comprises the protein according to claim 19 and a pharmaceutically acceptable carrier.
21 . The pharmaceutical composition according to claim 20 , which is an antitumor agent.