Single-step purification of human C4b-binding protein (C4BP) by affinity chromatography on a peptide derived from a streptococcal surface protein.

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Abstract

Many Gram-positive bacteria express surface proteins that bind human plasma proteins. These bacterial proteins, and derivatives of them, are of interest for analysis of bacterial pathogenesis and as immunochemical tools. Well-characterized examples include the IgG-binding reagents staphylococcal protein A and streptococcal protein G, and the recently described streptococcal IgA-binding peptide Sap. Here, we show that a peptide derived from the streptococcal M22 protein can be used for single-step affinity purification of the human complement regulator Cob-binding protein (C4BP). Binding of C4BP was strongly enhanced by dimerization of the peptide via a C-terminal cysteine residue not present in the intact M22 protein. The purified C4BP had the expected binding characteristics, and acted as a cofactor for factor I in the degradation of Cob. Passage of serum through a peptide column under non-saturating conditions resulted in binding of > 99.5% of serum C4BP, implying that such a column can be used to deplete serum of C4BP. These data indicate that the C4BP-binding peptide is a versatile tool that can be used for simple and rapid purification of biologically active human C4BP or for removal of C4BP from serum. (c) 2005 Elsevier B.V. All rights reserved.

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Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Immunology in the medical area

Keywords

  • depletion, peptide, streptococcal M protein, protein purification, C4BP
Original languageEnglish
Pages (from-to)83-95
JournalJournal of Immunological Methods
Volume297
Issue number1-2
Publication statusPublished - 2005
Publication categoryResearch
Peer-reviewedYes