Studies on the immobilization antigens of Paramecium. III. Properties.

Summary Immobilization antigen A from stock 51 of Paramecium aurelia has been characterized. It is largely or wholly protein, containing about 16% nitrogen, and possibly small amounts of carbohydrates. From 13 to 15 amino acids have been identified. It has a low electrophoretic mobility with an isoelectric point around pH 4.0. It has a diffusion coefficient of about 2.8 × 10 -7 cm 2 /sec, sedimentation coefficient of 8.3 Svedbergs, intrinsic viscosity of around 0.11 (g/100 ml), frictional ratio of 1.8, and molecular weight of around a quarter of a million. It9s properties indicate an asymmetric molecule.