streptococcal toxins

Group of haemolytic exotoxins released by Streptococcus spp. a -haemolysin: 26-39 Kd (four types), forms ring-like structures in membranes (see streptolysin O). Lipid target unclear; b -haemolysin: a hot-cold haemolysin with sphingomyelinase C activity; g -haemolysin: complex of two proteins (29 and 26 kD) that act synergistically, rabbit erythrocytes particularly sensitive; d -toxin: heat-stable peptide (5 kD) with high proportion of hydrophobic amino acids. Seems to act in a detergent-like manner (cf. subtilysin), but may form hydrophilic transmembrane pores by cooperative interaction with other d- toxin molecules; leucocidin (Panton-Valentine leucocidin) : two components F (fast migration on CM-cellulose column: 32 kD), and S (slow: 38 kD). Mode of action contentious. See also Streptococcus, streptolysins O and S, erythrogenic toxin.