Considerations in producing preferentially reduced half-antibody fragments.

Asta Makaraviciute, Carolyn Jackson, Paul Millner, Almira Ramanaviciene,

Journal of immunological methods, January 18, 2016

Half-antibody fragments are a promising reagent for biosensing, drug-delivery and labeling applications, since exposure of the free thiol group in the Fc hinge region allows oriented reaction. Despite the structural variations among the molecules of different IgG subclasses and those obtained from different hosts, only generalized preferential antibody reduction protocols are currently available. Preferential reduction of polyclonal sheep anti-digoxin, rabbit anti-Escherichia coli and anti-myoglobin class IgG antibodies to half-antibody fragments has been investigated. The mild reductant 2-mercaptoethylamine (2-MEA) and a slightly stronger reductant tris(2-carboxyethyl)phosphine (TCEP) were used and the fragments obtained were quantitatively determined by SDS-PAGE analysis. It has been shown that fragment yields of half-antibody fragments could be increased by lowering the pH of the reduction mixtures. However, antibody susceptibility to the reductants varied. At pH4.5 the highest yield of sheep anti-digoxin IgG half-antibody fragments was obtained with 1M 2-MEA. Conversely, rabbit IgG half-antibody fragments could only be obtained with the stronger reductant TCEP. Preferential reduction of rabbit anti-myoglobin IgG antibodies was optimized and the highest half-antibody yield was obtained with 35mM TCEP. Finally, it has been demonstrated that produced anti-myoglobin half-IgG fragments retained their binding activity.

Copyright © 2015. Published by Elsevier B.V.

Pubmed Link: 26779832

DOI: 10.1016/j.jim.2016.01.001