Purification of immunolobulin G Fc-reactive factor from Streptococcus azgazardah

A factor from Streptococcus azgazardah (Lancefield's group C) capable of reacting with the Fc fragment of human IgG was partially purified and characterized. The bacteria were lysed by infection with phage, and the IgG Fc-reactive factor was purified from the crude lysate by affinity chromatography on a IgG-coupled Sepharose 4B column. The column was eluted with 3 M KSCN and the eluate gel-filtered on a Sephadex G 75 column. A 30-fold purification was obtained. The molecular weight of the IgG Fc-reactive factor was estimated to be 60,000. The factor was sensitive to trypsin treatment and to heating 95 degrees C, 10 min at pH 2.0. On polyacrylamide electrophoresis only one band was obtained. The trypsin-and heat-sensitivity, and the estimated molecular weight of the factor was similar to an IgG Fc-reactive factor preparation obtained from group A, type M 56 streptococci by heat treatment at 120 degrees C for 30 min.