ウサギIgGのトリプシン限定分解について

抄録

Rabbit IgG antibodies against bacterial α-amylase were treated with trypsin in a medium free of any added reducing agent. The 5S fragments were isolated from the tryptic digest by fractionation with ammonium sulfate followed by gel filtration through Sephadex G-100. The tryptic 5S fragments could (I) form specific precipitate with corresponding antigen, (2) neutralizeamylase activity, (3) react with antiFab but not with anti-Fc sera, (4) fail to induce passive cutaneous anaphylaxis in guinea pigs. With these respects the tryptic 5S fragments were identified as divalent antibody fragments and were designated as F(ab")_2. The F(ab")_2 fragments were split into the 3.5S univalent fragments. The 3.5S fragments were also obtained by tryptic digestion in the presence of cysteine. The 3.5S univalent fragments closely resembled the papain 3.5S Fab fragments according to the antigenic analysis using goat antir-abbit globulin, Fab and Fc sera, and were designated as Fab" Homoreactants against Fab" or F(ab")_2 fragments from rabbit IgG could be demonstrated in the normal rabbit IgG by passive hemagglutination method. These homoreactants could be distinguished from homoreactants against Fab and Fab' reported by Mandy, W.J. The homoreactants against Fab" and Fab were partially purified with immunoadsorbents which were made by conjugating with Fab, Fab', Fab" insoluble poly-RSA by means of bis-diazotized benzidine method. These purified homoreactants showed specific binding activities with homologous immunoadsorbents. These activities were inhibited by homologous fragments but not or little by heterologous fragments. From these results, it is clear that antigenic differences among Fab, Fab', Fab" and F (ab")_2 can be demonstrated by the homoreactants present in normal rabbit serum.