内含肽的自剪接功能在生物药物合成制备方面有着不可估量的应用前景。我们前期在国家自然科学基金的支持下，在内含肽的结构和功能方面进行了研究，在双特异性抗体的制备技术平台等方面做了开创性的前期工作。这一技术平台利用分裂式内含肽的自剪接功能，将两段抗体、毒素分子或多肽分别合成，然后在体外温和条件下融合，发挥内含肽的剪接功能得到目标产品，再经亲和层析获得纯化。本项目研究中，我们将开展系统性的工作完善这一技术平台，并从两方面进行优化：1）筛选优化分裂式内含肽的N端和C端连接序列，达到提高合成效率；2）筛选抗体臂长，达到优化双特异性抗体的生物学活性。在此基础上，我们还将研究和优化利用内含肽介导合成双特异性免疫毒素和抗体偶联药物ADC的条件，以合成各类免疫杂合蛋白的药物验证此平台，以期最终应用于生产规模制备生物技术药物。

For its self-splicing acivity, intein has showed immeasurable promise in synthesizing biological drugs application. We have made significant progresses in understanding of the structure and function of intein with previous support from National Natural Science Foundation of China. The pioneering works has been done to construct of bi-specific antibodies using split-intein, which will serve as a novel platform to produce multi-specific immuno-hybrid proteins for biopharmaceutical applications. By using of the self-splicing function of split-intein, this technology platform can potentially not only efficiently generate bi-specific antibodies, but also site-specifically conjugate drugs, peptide toxins, cytokines, and other functional molecules. The new produced fusion molecules can be further get purified by affinity chromatography. In this project, we will perform systemic studies to accomplish this platform. There are two aspects to focus on: 1) optimization of the amino acids at the key postitions of the intein-anbidoy junction, to improve the splicing efficiency ot the platform; 2) optimization of the length and flexibility of the chains of antibodies, to improve the in vivo anti-tumor activity of the bi-specific and multi-specific drugs. Furthermore, we will apply this technology platform to construct the novel multi-specific antibody drug conjugates (ADCs) and immunotoxins to validate the system, in the hope of its application in the large scale production of biotech drugs.