The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here:

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Portrait of Tommy Cedervall; Photo: Kennet Ruona

Tommy Cedervall

Associate Professor, Coordinator Nanosafety

Portrait of Tommy Cedervall; Photo: Kennet Ruona

Allosteric and temperature effects on the plasma protein binding by streptococcal M protein family members


  • T Cedervall
  • P Akesson
  • L Stenberg
  • A Herrmann
  • B Akerström

Summary, in English

Most group A streptococcal strains bind immunoglobulins (Ig) and fibrinogen to their cell walls. It is shown in this paper that the Ig-binding of three different strains was much weaker at 37 degrees C than at room temperature (20 degrees C), whereas the fibrinogen binding was unaffected by temperature. The binding properties and molecular sizes of two purified group A streptococcal cell surface proteins from the M protein family were studied at various temperatures, M1 protein with affinity for IgG, fibrinogen and albumin, and protein Sir22 with affinity for IgA and IgG. Both proteins appeared as monomers which bound all their ligands, including fibrinogen, very weakly at 37 degrees C, and as strongly binding dimers at 10 and 20 degrees C. Furthermore, the results demonstrated that the plasma protein binding of the bacterial proteins was allosterically regulated, i.e. the binding of a ligand to one site modulated the binding of a ligand to a second site. For example, the binding of albumin or IgG to purified M1 protein at 10 and 20 degrees C strongly enhanced the binding of fibrinogen at 37 degrees C. This indicates that the high affinity dimer form of the bacterial proteins can be stabilized at 37 degrees C, a possible explanation for the strong fibrinogen binding of whole bacteria. Finally, the sizes and binding properties of three M1 protein fragments were studied and the results indicated that the centrally located C-repeats, which are conserved among the members of the M protein family, are important for the formation of the high-affinity dimers of the bacterial proteins.


  • Biochemistry and Structural Biology
  • Faculty of Medicine
  • Clinical Chemistry, Malmö
  • Department of Experimental Medical Science
  • Infection Medicine (BMC)

Publishing year







Scandinavian Journal of Immunology





Document type

Journal article




  • Immunology in the medical area


  • Allosteric Regulation
  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins/chemistry
  • Blood Proteins/chemistry
  • Carrier Proteins/chemistry
  • Humans
  • Streptococcus/metabolism
  • Temperature



Research group

  • Clinical Chemistry, Malmö


  • ISSN: 0300-9475