| 摘要 |
The present invention relates to a method of producing a modified protein having an increased stability and/or improved folding efficiency as compared to the unmodified protein, the method comprising (i) modifying a nucleic acid molecule encoding a protein comprising at least one immunoglobulin constant domain-like region by (a-i) replacing the nucleotides encoding at least one amino acid, preferably an uncharged amino acid, in the loop separating the C strand from the D strand with nucleotides encoding a charged amino acid selected from the group consisting of Arg, Lys, His, Glu and Asp and/or replacing the nucleotides encoding at least one amino acid, preferably an uncharged amino acid, in the helix connecting the E strand with the F strand with nucleotides encoding a charged amino acid selected from the group consisting of Arg, Lys, His, Glu and Asp; (a-ii) replacing the nucleotides encoding at least one amino acid not having a side chain that can form a hydrogen bond in the loop separating the C strand from the D strand with nucleotides encoding an amino acid having a side chain capable of forming a hydrogen bond selected from the group consisting of Gln, Asn, Tyr, Ser and Thr and/or replacing the nucleotides encoding at least one amino acid not having a side chain that can form a hydrogen bond in the helix connecting the E strand with the F strand with nucleotides encoding an amino acid having a side chain capable of forming a hydrogen bond selected from the group consisting of Gln, Asn, Tyr, Ser and Thr; and/or (a-iii) replacing the nucleotides encoding at least one amino acid in the loop separating the C strand from the D strand with nucleotides encoding a cysteine and/or replacing the nucleotides encoding at least one amino acid in the helix connecting the E strand with the F strand with nucleotides encoding a cysteine; and/or (b) replacing the nucleotides encoding at least one non-hydrophobic amino acid at a position suitable to participate in the formation of the hydrophobic core with nucleotides encoding a hydrophobic amino acid selected from the group consisting of Val, Ile, Leu, Met, Phe, Trp and Pro; and (ii) expressing the nucleic acid molecule to produce the stabilised protein. The present invention further relates to a method of producing a modified protein having an improved secretion from cells as compared to the unmodified protein, as well as to a protein comprising at least one immunoglobulin constant domain-like region having an additional salt bridge, an additional hydrogen bond, an additional disulfide bridge and/or an extended hydrophobic core. The present invention further relates to a nucleic acid molecule encoding the modified protein of the invention, as well as a vector comprising said nucleic acid molecule and a host cell comprising the vector. Further, the present invention relates also to a composition as well as to a kit. |
