Biochemistry. 2021 Apr 13;60(14):1080-1087. doi: 10.1021/acs.biochem.0c00955. Epub 2021 Mar 23.
Monoclonal antibody h38C2 is a humanized catalytic antibody that has been used to generate various immunoconjugate species such as chemically programmed antibodies, antibody-drug conjugates, and antibody-siRNA conjugates. Highly efficient and specific conjugation of h38C2 occurs at its uniquely reactive lysine (Lys) residue buried inside the antibody's catalytic pocket. We recently reported the rational mutation of this Lys residue at position 99 in the heavy chain variable domain to an arginine (Arg) residue. The Lys99Arg mutation can be site-selectively conjugated with molecules containing a hapten-like triazolyl-phenylglyoxal (TPG) unit. Here we show that this conjugation is facilitated by the unusual pH-sensitive reactivity of the Arg99 residue, consistent with an indirectly measured p of 5.2. The Arg99/TPG conjugation holds promise to further expand the versatility of the h38C2 conjugation platform, such as for the generation of antibody conjugates with dual payloads.
单克隆抗体 h38C2 是一种人源化的催化抗体，已被用于生成各种免疫缀合物，如化学编程抗体、抗体药物偶联物和抗体-siRNA 偶联物。h38C2 高度有效地和特异性地在其独特的反应性赖氨酸（Lys）残基处发生反应，该赖氨酸残基埋藏在抗体的催化口袋内。我们最近报道了在重链可变区的位置 99 处将该 Lys 残基理性突变突变为精氨酸（Arg）残基。Lys99Arg 突变可以与含有类半抗原的三唑基-苯甘氨酸（TPG）单元的分子进行位点选择性缀合。在这里，我们表明这种缀合是由 Arg99 残基的异常 pH 敏感反应性促成的，与间接测量的 p 值为 5.2 一致。Arg99/TPG 缀合有望进一步扩展 h38C2 缀合平台的多功能性，例如生成具有双重有效载荷的抗体缀合物。
