Immunoglobulin binding protein, and affinity support using same

Abstract

Provided are a protein L-derived immunoglobulin binding protein having an increased antibody dissociation rate under acidic conditions, and an affinity support using the same. Disclosed are an immunoglobulin binding protein comprising at least one mutant of an immunoglobulin binding domain, and an affinity support comprising a solid-phase support having the immunoglobulin binding protein bound thereto. A mutant of the immunoglobulin binding domain consists of an amino acid sequence having an identity of at least 85% with the sequence set forth in any one of SEQ ID NO:1 to SEQ ID NO:9 and a predetermined mutation, and the mutant has immunoglobulin chain binding activity.

Claims

1. An immunoglobulin binding protein, comprising at least one mutant of an immunoglobulin binding domain, wherein the at least one mutant of the immunoglobulin binding domain consists of an amino acid sequence having an identity of at least 95% with the sequence set forth in SEQ NO:9, the amino acid sequence having substitution of lysine at a position corresponding to the 26.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 34.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with histidine, and optionally at least one of substitution of threonine at a position corresponding to the 35.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 42.sup.nd position of the amino acid sequence set forth in SEQ ID NO:9 with lysine, and substitution of asparagine at a position corresponding to the 54.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with glutamine.

2. A polynucleotide encoding the immunoglobulin binding protein according to claim 1.

3. A vector, comprising the polynucleotide according to claim 2.

4. A transformant, transformant, comprising the vector according to claim 3.

5. An affinity support, comprising a solid-phase support; and the immunoglobulin binding protein according to claim 1 bound to the solid-phase support.

6. A method, comprising: isolating an antibody or a fragment thereof with the affinity support according to claim 5.

7. Method for producing an immunoglobulin binding protein, the method comprising: expressing the immunoglobulin binding protein according to claim 1 in a transformant comprising a vector comprising a polynucleotide encoding the immunoglobulin binding protein or a cell-free protein synthesis system, or chemically synthesizing the immunoglobulin binding protein.

8. A method for producing a mutant of an immunoglobulin binding domain, the method comprising: providing a polypeptide consisting of the amino acid sequence set forth in SEQ ID NO: 9 or an amino acid sequence having an identity of at least 95% therewith, introducing into the polypeptide at least one mutation selected from the group consisting of substitution of lysine at a position corresponding to the 26.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 34.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with histidine, and optionally at least one of substitution of threonine at a position corresponding to the 35.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 42.sup.nd position of the amino acid sequence set forth in SEQ ID NO:9 with lysine, and substitution of asparagine at a position corresponding to the 54.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with glutamine, to produce a mutant immunoglobulin binding domain having immunoglobulin chain binding activity.

9. A method for producing an affinity support, the method comprising: immobilizing the immunoglobulin binding protein according to claim 1 on a solid-phase support.

10. The immunoglobulin binding protein according to claim 1, wherein the amino acid sequence has substitution of lysine at a position corresponding to the 26.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 34.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with histidine, and substitution of threonine at a position corresponding to the 35.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine.

11. The immunoglobulin binding protein according to claim 1, wherein the amino acid sequence has substitution of lysine at a position corresponding to the 26.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 34.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with histidine, and substitution of glycine at a position corresponding to the 42.sup.nd position of the amino acid sequence set forth in SEQ II) NO:9 with lysine.

12. The immunoglobulin binding protein according to claim 1, wherein the amino acid sequence has substitution of lysine at a position corresponding to the 26.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 34.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with histidine, and substitution of asparagine at a position corresponding to the 54.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with glutamine.

13. The immunoglobulin binding protein according to claim 1, wherein the amino acid sequence has substitution of lysine at a position corresponding to the 26.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 34.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with histidine, substitution of threonine at a position corresponding to the 35 position of the amino acid sequence set forth in SEQ ID NO:9 with arginine, substitution of glycine at a position corresponding to the 42.sup.nd position of the amino acid sequence set forth in SEQ NO:9 with lysine, and substitution of asparagine at a position corresponding to the 54.sup.th position of the amino acid sequence set forth in SEQ ID NO:9 with glutamine.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described more specifically by way of Examples. Furthermore, the following description discloses embodiments of the present invention in a general manner, and unless particularly stated otherwise, the present invention is not intended to be limited by such description.

Example 1: Production of Immunoglobulin Chain Binding Proteins (KBP1 to KBP14)

(2) Plasmids in which each of genes encoding the proteins comprising a plurality of immunoglobulin binding domain mutants (mutated domains) each consisting of an amino acid sequence set forth in any one of SEQ ID NO: 10 to SEQ ID NO:23 had been inserted into ET-24a (+) vector, were purchased from an artificial gene synthesis manufacturer. Escherichia coli competent cells BL21 (DE3) (manufactured by New England Biolabs, Ltd.) were transformed with each of these plasmids, and thus transformed cells were obtained.

(3) The transformed cells thus obtained were incubated at 37 C. until the absorbance (OD600) reached about 1.0. Subsequently, IPTG (manufactured by Sigma-Aldrich Corp.) was added thereto so as to obtain a final concentration of 1 the culture was incubated for 4 hours at 37 C., and thereby a recombinant type immunoglobulin light chain binding protein was expressed. The cells were collected and disrupted in a Tris buffer solution at pH 9.5. From the disrupted cell suspension thus obtained, the recombinant immunoglobulin binding protein was purified by anion exchange chromatography (Q-SEPHAROSE FF, manufactured by GE Healthcare Biosciences Corp.) and cation exchange chromatography (SP-SEPHAROSE FF, manufactured by GE Healthcare Biosciences Corp.) The immunoglobulin binding protein thus purified was dialyzed for 16 hours against a 10 mM citric acid buffer solution at pH 6.6. The purity of the recombinant type immunoglobulin binding proteins were determined by SDS-PAGE to be 95% or higher. The recombinant immunoglobulin light chain binding proteins thus purified were designated as KBP1 to KBP14, respectively.

Comparative Example 1: Production of Immunoglobulin Light Chain Binding Protein (KBP0)

(4) Recombinant type immunoglobulin light chain binding protein KBP0 was produced by a procedure similar to Example 1 using a plasmid in which a gene encoding a protein comprising a plurality of wild type immunoglobulin binding domains each consisting of an amino acid sequence set forth in SEQ ID NO:9 had been inserted.

(5) The structures of the immunoglobulin light chain binding proteins (KBP0 to KBP14) produced in Example 1 and Comparative Example 1 are presented in Table 2.

Test Example 1: Measurement of Antibody Dissociation Rate of Immunoglobulin Binding Protein

(6) The dissociation rates of the immunoglobulin binding proteins produced in Example 1 and Comparative Example 1 from human IgG under acidic conditions were measured. The measurement was carried out by the following procedure using a column packed with IgG Sepharose 6 Fast Flow (manufactured by GE Healthcare Biosciences Corp.) (hereinafter, IgG column). First, an IgG column was mounted in AKTAprime plus (manufactured by GE Healthcare Biosciences Corp.), and the IgG column was equilibrated with an aqueous solution (binding buffer) of 20 mM sodium phosphate (manufactured by Wako Pure Chemical Industries, Ltd.)/150 mM sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.). An immunoglobulin binding protein of Example 1 or Comparative Example 1 was allowed to flow through this IgG column to adsorb to the column. The column was washed with the binding buffer, subsequently the column was brought into contact with a 50 mM aqueous solution of sodium citrate at pH 3.0 and then with a 50 mM aqueous solution of sodium citrate at pH 2.5, and thereby the immunoglobulin binding protein was dissociated from IgG Sepharose 6 Fast Flow. The peak area of the dissociated immunoglobulin binding protein was measured using PrimeView Evaluation (manufactured by GE Healthcare Biosciences Corp.) The antibody dissociation rate of the immunoglobulin binding protein of Example 1 or Comparative Example 1 at pH 3.0 was calculated by the following formula.
Antibody dissociation rate at pH 3.0=A/(A+B)

(7) A: Peak area of immunoglobulin binding protein dissociated at pH 3.0

(8) B: Peak area of immunoglobulin binding protein dissociated at pH 2.5

(9) The results are presented in Table 2. In the proteins KBP1 to KBP14 comprising mutated domains, the antibody dissociation rates at pH 3.0 were higher compared to the protein KBP0 comprising a wild type domain. Furthermore, the total amount of the amounts of dissociation between the immunoglobulin binding protein and the antibody to be evaluated from the peak measurement values under the conditions of pH 3.0 and the conditions of pH 2.5 was equal in KBP0 and KBP1 to KBP14. From these results, it was found that this antibody dissociation behavior enhanced in the KBP1 to KBP14 comprising mutated domains under acidic conditions of pH 3.0. It was found by an affinity test using these mutated domains that an antibody can be efficiently dissociated from a ligand even under relatively mild conditions of about pH 3.0.

(10) TABLE-US-00002 TABLE 2 Antibody Mutated Number dissociation domain Parent Introduced of rate (%) at Name sequence domain mutation domains pH 3.0 KBPO C4 (SEQ 4 50 KBP1 SEQ ID ID NO: 9) I16H 4 95 NO: 10 KBP2 SEQ ID V18H 4 98 NO: 11 KBP3 SEQ ID L2OH 4 95 NO: 12 KBP4 SEQ ID Q28H 4 95 NO: 13 KBP5 SEQ ID A30H 4 92 NO: 14 KBP6 SEQ ID F32H 4 92 NO: 15 KBP7 SEQ ID G34H 4 97 NO: 16 KBP8 SEQ ID E38K 4 80 NO: 17 KBP9 SEQ ID E42K 4 95 NO: 18 KBP10 SEQ ID Y57H 4 97 NO: 19 KBP11 SEQ ID I70H 4 99 NO: 20 KBP12 SEQ ID K26R, G34H, 4 100 NO: 21 T35R, E42K, N54Q KBP13 SEQ ID K26R, T35R, 4 100 NO: 22 E42K, N54Q, Y57H KBP14 SEQ ID K26R, F32H, 4 100 NO: 23 T35R, E42K, N54Q