The present invention relates to an immunoglobulin-binding protein, wherein at least one asparagine residue has been mutated to an amino acid other than glutamine or aspartic acid, which mutation confers an increased chemical stability at pH-values of up to about 13-14 compared to the parental molecule. The protein can for example be derived from a protein capable of binding to other regions of the immunoglobulin molecule than the complementarity determining regions (CDR), such as protein A, and preferably the B-domain of Staphylococcal protein A. The invention also relates to a matrix for affinity separation, which comprises an immunoglobulin-binding protein as ligand coupled to a solid support, in which protein ligand at least one asparagine residue has been mutated to an amino acid other than glutamine.

The present disclosure provides customizable enucleated erythroid cells or enucleated cells that can be engineered to include, on their surface, a loadable exogenous antigen-presenting polypeptide, wherein the loadable exogenous antigen-presenting polypeptide comprises one or more amino acid substitutions. In some embodiments, the one or more amino acid substitutions stabilize the loadable exogenous antigen-presenting polypeptide on the cell surface. In some embodiments, the loadable exogenous antigen-presenting polypeptide is stabilized on the cell surface in the absence of a polypeptide bound to the loadable exogenous antigen-presenting polypeptide. In some embodiments, the loadable exogenous antigen-presenting polypeptide comprises an exogenous displaceable polypeptide bound to the loadable exogenous antigen-presenting polypeptide. In some embodiments, the loadable exogenous antigen-presenting polypeptide is stabilized on the cell surface upon release of the displaceable polypeptide.

The present invention relates to an immunoglobulin-binding protein, wherein at least one asparagine residue has been mutated to an amino acid other than glutamine or aspartic acid, which mutation confers an increased chemical stability at pH-values of up to about 13-14 compared to the parental molecule. The protein can for example be derived from a protein capable of binding to other regions of the immunoglobulin molecule than the complementarity determining regions (CDR), such as protein A, and preferably the B-domain of Staphylococcal protein A. The invention also relates to a matrix for affinity separation, which comprises an immunoglobulin-binding protein as ligand coupled to a solid support, in which protein ligand at least one asparagine residue has been mutated to an amino acid other than glutamine.

The present invention relates to an immunoglobulin-binding protein, wherein at least one asparagine residue has been mutated to an amino acid other than glutamine or aspartic acid, which mutation confers an increased chemical stability at pH-values of up to about 13-14 compared to the parental molecule. The protein can for example be derived from a protein capable of binding to other regions of the immunoglobulin molecule than the complementarity determining regions (CDR), such as protein A, and preferably the B-domain of Staphylococcal protein A. The invention also relates to a matrix for affinity separation, which comprises an immunoglobulin-binding protein as ligand coupled to a solid support, in which protein ligand at least one asparagine residue has been mutated to an amino acid other than glutamine.

A metal-binding protein having a high selective affinity for certain trivalent cations and/or tetravalent cations derived from, for example, rare earth elements or ions thereof such as lanthanide elements and actinides or ions thereof as well as from hafnium and zirconium elements or compounds thereof is disclosed as well as sensors including same and methods for capturing and separating such trivalent cations and/or tetravalent cations using the metal-binding protein.