Structural models for carcinoembryonic antigen and its complex with the single-chain Fv antibody molecule MFE23

MFE23 is a single chain Fv antibody that has a high affinity for carcinoemb ryonic antigen (CEA), A full homology model for CEA based on V-type, I-type and C2-type immunoglobulin folds, 28 oligosaccharides and the interdomain angle of CD2 was validated using solution scattering data. The super-imposi tion of the intermolecular contacts observed in our recent crystal structur e of MFE23 with the N-terminal domain of CEA permitted the MFE23-CEA comple x to be modelled. Good surface and electrostatic complementarity and carboh ydrate-unhindered access of MFE23 with the indentation between the first tw o CEA domains was observed. The model is supported by biochemical data and provides insight on the high affinity of MFE23 for CEA. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.