Immunoglobulin-binding protein and affinity support using same
An affinity support having improved binding capacity for target proteins. An immunoglobulin-binding protein including a mutant immunoglobulin-binding domain, an affinity support including a solid-phase support and the immunoglobulin-binding protein immobilized thereto. The mutant immunoglobulin-binding domain consists of an amino acid sequence having at least 85% identity with an amino acid sequence of any of SEQ ID NOs: 1 to 12.
1 . An affinity support, comprising:
a solid-phase support, and
an immunoglobulin-binding protein immobilized onto the solid-phase support,
the immunoglobulin-binding protein comprising a mutant immunoglobulin-binding domain, and
the mutant immunoglobulin-binding domain consisting of an amino acid sequence having at least 85% identity with an amino acid sequence of any of SEQ ID NOs: 1 to 12,
wherein the amino acid sequence of the mutant immunoglobulin-binding domain has at least one mutation selected from the group consisting of the following mutations (a) to (d):
(a) a substitution of Lys with another amino acid residue, a deletion of Lys, or an insertion of another amino acid residue at a position before or after Lys at a position corresponding to position 58 of the amino acid sequence of SEQ ID NO: 3;
(b) a substitution of Lys with another amino acid residue, a deletion of Lys, or an insertion of another amino acid residue at a position before or after Lys at a position corresponding to position 50 of the amino acid sequence of SEQ ID NO: 3;
(c) a substitution of Lys with another amino acid residue, a deletion of Lys, or an insertion of another amino acid residue at a position before or after Lys at a position corresponding to position 49 of the amino acid sequence of SEQ ID NO: 3; and
(d) a substitution of Lys with another amino acid residue, a deletion of Lys, or an insertion of another amino acid residue at a position before or after Lys at a position corresponding to position 42 of the amino acid sequence of SEQ ID NO: 3, and
the amino acid sequence of the mutant immunoglobulin-binding domain has Lys at at least one position selected from the group consisting of positions corresponding to positions 4, 7, and 35 in the amino acid sequence of SEQ ID NO: 3,
wherein the solid-phase support and the immunoglobulin-binding protein are immobilized via a linker,
the linker comprises a polyethylene glycol chain and an epoxy group, a carboxy group, a (meth)acrylic group, an aldehyde group, or a succinimidyl group,
the linker has a length is from 40 to 300, wherein the linker length is the total of a chain length of the polyethylene glycol chain and the number of carbon atoms derived from the epoxy group, carboxy group, a (meth)acrylic group, an aldehyde group, or a succinimidyl group.
2 . The affinity support of claim 1 , wherein the mutant immunoglobulin-binding domain consists of an amino acid sequence having at least 85% identity with the amino acid sequence of SEQ ID NO: 3 or 9.
3 . The affinity support of claim 1 , wherein:
the mutation (a) is a substitution of Lys by Arg, a deletion of Lys, or an insertion of Arg at a position before Lys at a position corresponding to position 58 of the amino acid sequence of SEQ ID NO: 3;
the mutation (b) is a substitution of Lys by Arg, a deletion of Lys, or an insertion of Arg at a position before Lys at a position corresponding to position 50 of the amino acid sequence of SEQ ID NO: 3;
the mutation (c) is a substitution of Lys by Arg, a deletion of Lys, or an insertion of Arg at a position before Lys at a position corresponding to position 49 of the amino acid sequence of SEQ ID NO: 3; and
the mutation (d) is a substitution of Lys by Arg, a deletion of Lys, or an insertion of Arg at a position before Lys at a position corresponding to position 42 in the amino acid sequence of SEQ ID NO: 3.
4 . The affinity support of claim 1 , wherein the amino acid sequence of the mutant immunoglobulin-binding domain has the mutation (a).
5 . The affinity support of claim 4 , wherein the mutant immunoglobulin-binding domain has Arg at a position corresponding to position 58 of the amino acid sequence of SEQ ID NO: 3.
6 . The affinity support of claim 1 , wherein the amino acid sequence of the mutant immunoglobulin-binding domain has at least 90% identity with the amino acid sequence of any of SEQ ID NOs: 1 to 12.
7 . The affinity support of claim 1 , wherein the amino acid sequence of the mutant immunoglobulin-binding domain further has at least one amino acid residue selected from the group consisting of Val at a position corresponding to position 1 of the amino acid sequence of SEQ ID NO: 3 and Ala at a position corresponding to position 29 of the amino acid sequence of SEQ ID NO: 3.
8 . The affinity support of claim 1 , wherein the immunoglobulin-binding protein comprises two or more immunoglobulin-binding domains.
9 . A chromatography column, comprising the affinity support of claim 1 .
10 . A method of isolating an antibody or a fragment thereof, comprising using the affinity support of claim 1 or a chromatography column comprising the affinity support.
11 . The affinity support of claim 1 , wherein the linker comprises the epoxy group.
12 . The affinity support of claim 1 , wherein the linker is a bifunctional epoxy compound comprising the polyethylene glycol chain and the epoxy group,
wherein the linker length is the total of the chain length of the polyethylene glycol chain and the number of carbon atoms derived from the epoxy group.