Purification and properties of a receptor for the Fc-component of immunoglobulin G from Streptococcus dysgalactiae.

A receptor for the Fc-component (FcR) of immunoglobulin (Ig) G was isolated from the cell-free supernatant of a Streptococcus dysgalactiae-culture by affinity chromatography on human IgG-sepharose. The single-step procedure yielded purified FcR with a specific activity of 1.1 x 10(6) U/mg protein. It had an estimated molecular weight of 78 000 dalton and an isoelectric point between pH 4.0 and 4.5. It was destroyed by pronase E and was sensitive to trypsin. Purified FcR gave strong single precipitin lines in the double immunodiffusion test with sera from human, horses, cattle, pigs, sheep, rabbits and guinea pigs. It also reacted with human IgG subgroup 3, differing from protein A of Staphylococcus aureus.