A Selective Fractionation of Anti-Lysozyme Antibodies of Different Determinant Specificities

Antibodies to lysozyme were selectively fractionated by the use of an immunoadsorbent prepared with a peptic fragment of the enzyme, and a subsequent purification of the remaining antibodies in the serum. Both fractions of antibodies reacted immunologically with lysozyme as checked by antigen-combining and passive cutaneous anaphylaxis tests, but only the second fraction precipitated with it. Both fractions inhibited the catalytic activity of lysozyme, on a large substrate (Micrococcus lysodeikticus) as well as on a substrate of small molecular weight (pentasaccharide), but to a lesser extent than the total antibody population. It is concluded that in the lysozyme-antilysozyme system the inhibition by the antibodies is due to steric hindrance alone. The greater inhibitory efficiency of the unfractionated antilysozyme antibodies, seems due to simultaneous combination of the enzyme with several antibody molecules of different specificities.