Poly-histidine peptides such as H6 (HHHHHH) are used in protein biotechnologies as purification tags, protein-assembling agents and endosomal-escape entities. The pleiotropic properties of such peptides make them appealing to design protein-based smart materials or nanoparticles for imaging or drug delivery to be produced in form of recombinant proteins. However, the clinical applicability of H6-tagged proteins is restricted by the potential immunogenicity of these segments. In this study, we have explored several humanized histidine-rich peptides in tumor-targeted modular proteins, which can specifically bind and be internalized by the target cells through the tumoral marker CXCR4. We were particularly interested in exploring how protein purification, self-assembling and endosomal escape perform in proteins containing the variant histidine-rich tags. Among the tested candidates, the peptide H5E (HEHEHEHEH) is promising as a good promoter of endosomal escape of the associated full-length protein upon endosomal internalization. The numerical modelling of cell penetration and endosomal escape of the tested proteins has revealed a negative relationship between the amount of protein internalized into target cells and the efficiency of cytoplasmic release. This fact demonstrates that the His-mediated, proton sponge-based endosomal escape saturates at moderate amounts of internalized protein, a fact that might be critical for the design of protein materials for cytosolic molecular delivery.

诸如蛋白质H6（HHHHHH）的多组氨酸肽在蛋白质生物技术中用作纯化标签，蛋白质组装剂和逃逸内体的实体。此类肽的多效性使其吸引人们设计基于蛋白质的智能材料或纳米粒子，以成像或药物输送的形式以重组蛋白质的形式生产。但是，H6标签蛋白的临床适用性受到这些片段潜在的免疫原性的限制。在这项研究中，我们探索了肿瘤靶向模块蛋白中的几种人源化富含组氨酸的肽，它们可以通过肿瘤标记物CXCR4特异性结合并被靶细胞内化。我们对探索蛋白质纯化方法特别感兴趣，自组装和内体逃逸在含有富含组氨酸标签的变体的蛋白质中进行。在测试的候选物中，肽H5E（HEHEHEHEH）有望在内体内化后作为相关全长蛋白的内体逃逸的良好启动子。被测蛋白质的细胞渗透和内体逃逸的数值模型揭示了内化到靶细胞中的蛋白质数量与细胞质释放效率之间的负相关关系。这个事实表明，His介导的基于质子海绵的内体逃逸在中等量的内化蛋白质时达到饱和，这一事实对于设计用于胞质分子递送的蛋白质材料可能至关重要。H5E（HEHEHEHEH）肽有望在内体内化后作为相关全长蛋白的内体逃逸的良好启动子。被测蛋白质的细胞渗透和内体逃逸的数值模型揭示了内化到靶细胞中的蛋白质数量与细胞质释放效率之间的负相关关系。这个事实表明，His介导的基于质子海绵的内体逃逸在中等量的内化蛋白质时达到饱和，这一事实对于设计用于胞质分子递送的蛋白质材料可能至关重要。H5E（HEHEHEHEH）肽有望在内体内化后作为相关全长蛋白的内体逃逸的良好启动子。被测蛋白质的细胞渗透和内体逃逸的数值模型揭示了内化到靶细胞中的蛋白质数量与细胞质释放效率之间的负相关关系。这个事实表明，His介导的基于质子海绵的内体逃逸在中等量的内化蛋白质时达到饱和，这一事实对于设计用于胞质分子递送的蛋白质材料可能至关重要。被测蛋白质的细胞渗透和内体逃逸的数值模型揭示了内化到靶细胞中的蛋白质数量与细胞质释放效率之间的负相关关系。这个事实表明，His介导的基于质子海绵的内体逃逸在中等量的内化蛋白质时达到饱和，这一事实对于设计用于胞质分子递送的蛋白质材料可能至关重要。被测蛋白质的细胞渗透和内体逃逸的数值模型揭示了内化到靶细胞中的蛋白质数量与细胞质释放效率之间的负相关关系。这个事实表明，His介导的基于质子海绵的内体逃逸在中等量的内化蛋白质时达到饱和，这一事实对于设计用于胞质分子递送的蛋白质材料可能至关重要。