Comparison of physical chemical properties of llama VHH antibody fragments and mouse monoclonal antibodies

Antigen specific llama V-HH antibody fragments were compared to antigen specific mouse monoclonal antibodies with respect to specificity, affinity and stability. The llama V-HH antibody fragments and the mouse monoclonal antibodies investigated were shown to be highly specific for the protein antigen hCG or the hapten antigen RR-6. The affinity of the interaction between monovalent llama V-HH antibody fragments and their antigen is close to the nanomolar 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 monoclonal antibodies, antigen specific llama V-HH fragments are extremely temperature stable. Two out of six llama V(HH)s are able to bind antigen specifically 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 Saccharomyces cerevisiae, there findings indicate that in the near future antigen specific llama V-HH fragments can be used in for antibodies unexpected products and processes. (C) 1999 Elsevier Science B.V. All rights reserved.