Structural features of the McPC603 F_ab fragment not defined in the X‐ray structure

Abstract

The proteolytic F,, fragment of the well characterized antibody McPC603 was compared to the recombinant Fab fragment, which was obtamed in functional form from an Escherichiu coli expression system [(l989) Methods Enzymol. 178, 497-5151. We found evidence that the proteolytic fragment is glycosylated at Asn HI60 in the CHI domain, where additional electron density had been observed in the crystal structure [J. Mol. Biol. 190,. In addition, its heavy chain is about 30 amino acids longer than visible in the electron density and thus contains the complete hmge region. These structural differences between the recombinant F,,,, fragment, which had been designed exactly according to the defined electron density. and the proteolytic F ,%b fragment of McPC603 had no effect on the hapten binding properties of these antigen binding fragments. Yet, it may be important to be aware of these structural features of McPC603 in folding studies and some comparative analyses of antibody structures.

Mono‐ and Bivalent Antibody Fragments Produced in Escherichia coli: Engineering, Folding and Antigen Binding

“…Fab fragments of certain antibody classes may be glycosylated in CHI (NisonoPf et al 1975. Young et al 1990, Skerra et al 1990), but the most frequently used IgG molecules are nol. This glycosylation which can occur, for example, in mouse IgA, does not have any effect on the binding of the antigen (Skerra et ai.…”

Secretion and in vivo folding of the Fab fragment of the antibody McPC603 in Escherichia coli: influence of disulphides and cis-prolines

“…The antiserum used was obtained from rabbits immunized either with the intact antibody McPC603 purified. from mouse ascites or with the proteolytically prepared Fab' fragment of this antibody Skerra et al, 1990). The immunoreactive bands were detected with pig anti-rabbit immunoglobulin conjugated with alkaline phosphatase (Dakopatts).…”

Biotechnological aspects of antibody production in E. coli

“…antibody [26]. Even the fact that the CHI domain is glycosylated in this mouse IgA has no effect on the antigen binding constant.…”