NCL with induced a-Helices: de Novo Chemical Synthesis of the ATAD2 bromodomain

描述（由申请人提供）：蛋白质的从头化学合成有可能通过提供快速获取天然和合理设计的非天然蛋白质的途径，迅速加速蛋白质的研究。然而，目前，由于一些实际因素，蛋白质的化学合成仅限于相对较小的多肽和糖肽。通常，肽片段的连接效率随着肽长度的增加而降低，其中肽聚集是经常观察到的障碍。我们提出了一种替代范例，用于保护肽免受聚集和天然结扎的大小限制，而不是引入外来的保护功能和辅助物。在溶液中诱导易于形成α -螺旋的肽片段的二级结构，应通过将肽主干硬化成紧凑的构象来保护肽免受破坏性聚集。这条推理路线与传统上仅在变性条件下进行的典型天然化学结扎方案形成鲜明对比。除了减少聚集倾向外，我们预计螺旋蛋白片段由于构象的紧密性和刚性而提高了连接效率，并且肽复杂性和连接效率之间的负相关关系相应降低。为了研究这种多肽连接的方法，我们将合成人蛋白ATAD2的溴结构域。仅在过去几年中，该蛋白已被发现在乳腺癌、前列腺癌、肺癌和卵巢肿瘤中表达上调，大量研究将ATAD2的过表达与癌症生长和患者预后联系起来。考虑到ATAD2参与蛋白质转录和有丝分裂，以及在多种肿瘤类型中观察到的上调，ATAD2被确定为潜在的治疗方法也就不足为奇了

DESCRIPTION (provided by applicant): The de novo chemical synthesis of proteins has the potential to rapidly accelerate the study of proteins by providing rapid access to natural and rationally designed unnatural proteins. Currently, however, chemical synthesis of proteins is limited to relatively small sized polypeptides and glycopeptides, due to a number of practical factors. Generally, the efficiency of ligation of peptide fragments decreases with increasing peptide length, where peptide aggregation is an often observed obstacle. We propose an alternative paradigm for the protection of peptides against aggregation and the size limitations of native ligation, in contrast to the introduction of extraneous protection functionalities and auxiliaries. The induction of secondary structure in solution for peptide fragments that are predisposed to the formation of alpha-helices should serve to protect the peptides against destructive aggregation by rigidifying the peptide backbone into a compact conformation. This line of reasoning is in stark contrast to the typical native chemical ligation protocol that is historically performed exclusively under denaturing conditions. In addition to reduced propensity towards aggregation, we expect the helical protein fragments to have increased efficiency of ligation due to the conformation compactness and rigidity, and a corresponding reduction in the negative correlation between peptide complexity and ligation efficiency. In order to investigate this approach towards peptide ligation, the bromodomain of human protein ATAD2 will be synthesized. In only the past few years, this protein has been identified as upregulated in breast, prostate, lung, and ovarian tumors, and numerous studies have correlated the over expression of ATAD2 with cancer growth and patient prognosis. Considering the involvement of ATAD2 with protein transcription and mitosis along with the upregulation observed in a wide variety of tumor types, it is no surprise that ATAD2 has been identified as a potential therapeutic target. The bromodomain of ATAD2 is an ideal target to test the helical stabilization hypothesis because it is made up of five alpha-helices, each of ideal size for solid phase peptide synthesis, and includes two relatively hydrophobic regions with potential for aggregation. This investigation has the potential for broad implications, as the strategic revision for the chemical synthesis of proteins that is proposed applies new rules for the disconnection of polypeptides into their corresponding fragments.