Comparison of physical chemical properties of llama V-HH antibody fragments and mouse monoclonal antibodies

Antigen specific llama V-HH antibody fragments were compared to antigen spe cific mouse monoclonal antibodies with respect to specificity, affinity and stability. The llama V-HH antibody fragments and the mouse monoclonal anti bodies investigated were shown to be highly specific for the protein antige n hCG or the hapten antigen RR-6. The affinity of the interaction between m onovalent llama V-HH antibody fragments and their antigen is close to the n anomolar range, similar to the bivalent mouse monoclonal antibodies studied . Llama V-HH antibody fragments are similar to mouse monoclonal antibodies with respect to antigen binding in the presence of ammonium thiocyanate and ethanol. The results show that relative to antigen specific mouse monoclon al antibodies, antigen specific llama V-HH fragments are extremely temperat ure stable. Two out of six llama V(HH)s are able to bind antigen specifical ly at temperatures as high as 90 degrees C, whereas four out of four mouse monoclonal antibodies are not functional at this temperature. Together with the finding that llama V-HH fragments can be produced at high yield in Sac charomyces cerevisiae, there findings indicate that in the near future anti gen specific llama V-HH fragments can be used in for antibodies unexpected products and processes. (C) 1999 Elsevier Science B.V. All rights reserved.