FORMATION OF DIMERIC FABS IN ESCHERICHIA-COLI - EFFECT OF HINGE SIZE AND ISOTYPE, PRESENCE OF INTERCHAIN DISULFIDE BOND, FAB' EXPRESSION LEVELS, TAIL PIECE SEQUENCES AND GROWTH-CONDITIONS

We have made hinge variants of two human Fab's in order to investigate the factors involved in the formation of dimeric Fab's in the peripla sm of E. coli. Hinges containing one or more copies of the IgG1 hinge with various numbers of spacing residues were tested. Fab's with hinge s based on the gamma 2, gamma 3 and gamma 4 isotypes were also tested. We find that the IgG1 hinge sequence can form approximately 35% F(ab' )(2) in vivo in shake flask experiments, but that only (approximately) 5% F(ab')(2) can be produced during fermentation. IgM and IgA tail-pi eces added to Fab's did not effect their multimerisation. The possible role of growth conditions upon F(ab')(2) formation in vivo is discuss ed. (C) 1997 Elsevier Science B.V.