CRYSTALLIZATION OF AN ANTITUMOR ANTIBODY SM3 COMPLEXED WITH A PEPTIDEEPITOPE

SM3 antibody binds to a tumour-associated epitope on polymorphic epith elial mucin (PEM). Crystals of the Fab fragment of SM3 in complex with a peptide antigen were obtained by vapour diffusion against mother li quor containing acetate buffer, pH 6.5, cadmium chloride and polyethyl ene glycol (PEG) 4000 as precipitating agent. Crystals belong to the m onoclinic space group P2(1) with cell dimensions a = 42.2, b = 83.9, c = 64.5 Angstrom and beta = 93.4 degrees. One Fab-antigen complex is p resent in the asymmetric unit. Diffracted intensities up to 1.95 Angst rom resolution have been measured from a frozen crystal using synchrot ron radiation.