Biologics, such as antibody–drug conjugates, are becoming mainstream therapeutics. Consequently, methods to functionalize biologics without disrupting their native properties are essential for identifying, characterizing, and translating candidate biologics from the bench to clinical practice. Here, we present a method for site-specific, carboxy-terminal modification of single-chain antibody fragments (scFvs). ScFvs displayed on the surface of yeast were isolated and functionalized by combining intein-mediated expressed protein ligation (EPL) with inverse electron-demand Diels–Alder (IEDDA) cycloaddition using a styrene–tetrazine pair. The high thiol concentration required to trigger EPL can hinder the subsequent chemoselective ligation reactions; therefore, the EPL reaction was used to append styrene to the scFv, limiting tetrazine exposure to damaging thiols. Subsequently, the styrene-functionalized scFv was reacted with tetrazine-conjugated compounds in an IEDDA cycloaddition to generate functionalized scFvs that retain their native binding activity. Rapid functionalization of yeast surface-derived scFv in a site-directed manner could find utility in many downstream laboratory and preclinical applications.
生物制剂,如
抗体-药物偶连物,正逐渐成为主流治疗方法。因此,开发在不破坏其天然特性的情况下功能化
生物制剂的方法,对于识别、表征和将候选
生物制剂从实验室转化到临床应用至关重要。在此,我们提出了一种对单链
抗体片段(scFv)进行特定位点、羧基末端修饰的方法。通过将内肽介导的表达蛋白连接(EPL)与反向电子需求Diels–Alder(IE
DDA)环加成结合,分离并功能化了显示在酵母表面的scFv,采用的是
苯乙烯-
四氮唑配对。触发EPL所需的高
硫醇浓度可能会妨碍后续的
化学选择性连接反应;因此,使用EPL反应将
苯乙烯附加到scFv上,从而限制了
四氮唑暴露于有害
硫醇中。随后,将
苯乙烯功能化的scFv与
四氮唑偶联化合物进行IE
DDA环加成反应,生成保留其天然结合活性的功能化scFv。以定点方式快速功能化酵母表面衍生的scFv,可能在许多下游实验室和临床前应用中具有实用性。