title: Quantitative differences in specific binding of fibrinogen fragment D by M-positive and M-negative group-A streptococci.
abstract: Selected M-positive and M-negative group-A streptococcal strains were investigated with respect to their selective absorption of plasmin fibrinogen degradation products (FDP) in a simple batch technique. After incubation of killed streptococci with the FDP mixture, the centrifuged supernatants were investigated by SDS-electrophoresis and the binding capacity of the strains was calculated by evaluation of the scanning curves of stained gels. It was found that there is a specific uptake of the C-terminal fragment D by both M-positive and M-negative strains. Although the M-positive strains bound more fragment D (30%-80%) than did the M-negative strains (10%-15%), it could be clearly shown that the loss of M-protein was not necessarily linked with a total disappearance of fibrinogen binding activity. Fragment D blocked the agglutination of streptococci by fibrinogen. Washing the streptococci preincubated with FDP with a 0.1 M citric acid, 6 M urea buffer, pH 3.0, restored agglutination. Treatment of FDP-incubated bacteria with this buffer was found to be a means of recovering pure fragment D from streptococcal cells. It is suggested that M-positive and M-negative streptococci have qualitatively similar binding sites. These receptors might be reduced in the M-negative streptococci. Human serum albumin and Tween 20 did not influence the interaction between streptococcus and fibrinogen.
mesh_terms: D000371:Agglutination; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism; D013297:Streptococcus pyogenes / Q000378:metabolism*
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005338:Fibrin Fibrinogen Degradation Products; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; C015214:fibrinogen D fragment; C014689:streptococcal M protein