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  • Heavy chain dimers stabilized by disulfide bonds are required to promote in vitro assembly of trastuzumab.

Heavy chain dimers stabilized by disulfide bonds are required to promote in vitro assembly of trastuzumab.

BMC molecular and cell biology (2020-01-23)
Mercè Farràs, Ramón Román, Marc Camps, Joan Miret, Óscar Martínez, Xavier Pujol, Antoni Casablancas, Jordi Joan Cairó
ABSTRACT

Monoclonal antibodies (mAbs) and their derivatives have become one of the most important classes of therapeutic drugs. Their multiple applications increased the interest for understanding their complex structure. In vivo, animal cells are able to fold mAbs correctly (Song et al, J Biosci Bioeng 110:135-40, 2010), whereas previous in vitro approaches were scarce and mostly unsuccessful. In this work, we compared in vitro assembly characteristics of trastuzumab, produced either by A) physical separation and refolding of its sub-units or B) direct joining of individually produced heavy and light chains. Native and denatured structures of trastuzumab were determined by SEC-HPLC, HIC-HPLC and SDS-PAGE. Our results demonstrate the requirement of correctly folded HC, forming disulfide-bonded dimers, in order to form a fully functional mAb. Otherwise, the unfolded HC tend to precipitate. We were able to assemble trastuzumab in this fashion by only mixing them to LC in pH-buffered conditions, while monomeric HC structure was too unstable to render a functional mAb. This approach has been used in the generation of homogeneous ADC, with results pending to be published.

MATERIALS
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Brand
Product Description

Sigma-Aldrich
Trisodium citrate dihydrate, meets USP testing specifications
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