PEGylation is a well-established technology for half-life extension in drug delivery. In this study, we aimed to develop a site-specific N-terminal PEGylation for biotherapeutics to achieve controlled release, using GLP-1 as a model. An additional threonine was introduced at N-terminal GLP-1. Followed by periodate oxidation, hydrazide-based PEGylation was achieved in a site-selective manner under reductive condition. Two homogenous monovalent mPEG_5k-GLP-1 (peptide 4) and mPEG_20k-GLP-1 (peptide 5) were successfully constructed. After PEGylation, the degradation by DPP-IV and rat plasma was obviously reduced. Their pharmacokinetic performances were enhanced at the expense of impaired GLP-1R stimulating potency, and their hypoglycemic effects were improved in different degrees. Compared with conventional strategies, this approach is devoid of the restriction and alteration of native peptide sequences, and can produce utterly homogenous conjugates with excellent selectivity and efficiency. It provides a practical controlled release approach for peptides by site-specific modification to achieve better pharmacological and therapeutic properties.

聚乙二醇化是一种成熟的药物递送半衰期延长技术。在这项研究中，我们旨在使用 GLP-1 作为模型，开发一种用于生物治疗药物的位点特异性 N 端聚乙二醇化以实现控释。在 N 端 GLP-1 引入了额外的苏氨酸。在高碘酸盐氧化之后，在还原条件下以位点选择性的方式实现了基于酰肼的聚乙二醇化。两个同质的单价 mPEG _5k -GLP-1（肽4）和 mPEG _20k -GLP-1（肽5) 构建成功。PEG化后，DPP-IV和大鼠血浆的降解明显降低。其药代动力学性能增强，但GLP-1R刺激效力受损，降血糖作用均有不同程度的改善。与传统策略相比，这种方法没有天然肽序列的限制和改变，可以产生完全同源的偶联物，具有优异的选择性和效率。它通过位点特异性修饰为肽提供了一种实用的控释方法，以实现更好的药理和治疗特性。