Protein carbamylation has been linked with diseases commonly associated with patients with reduced kidney function. Carbamylated human serum albumin (cHSA), which has been proven to be nephrotoxic and associated with heart failure for chronic kidney disease (CKD) patients, was chosen for our study. Through phage display against cHSA, one specific peptide sequence (cH2-p1) was identified with higher selectivity toward cHSA over native HSA. The cH2-p1 peptide was synthesized, and its target binding was analyzed through isothermal titration calorimetry (ITC). The result showed that cH2-p1 was able to bind cHSA of different levels of carbamylation with a similar dissociation constant of ∼1.0 × 10^–4 M. This peptide also showed a binding specificity to carbamylated fibrinogen (cFgn), while not binding to native Fgn at all. For better understanding of the binding mechanism of cH2-p1, competitive binding of cH2-p1 and anti-homocitrulline to cHSA was performed, and the result revealed that cH2-p1 may bind to homocitrulline residues in a similar manner to the antibody. A molecular docking study was further performed to investigate the favored binding conformation of homocitrulline residue to cH2-p1. This work demonstrates the potential of peptides as a specific binding element to carbamylated proteins.

中文翻译：

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特定于氨基甲酰化蛋白的噬菌体展示肽

蛋白氨基甲酸酯化与通常与肾功能降低的患者有关的疾病有关。我们的研究选择了氨基甲酸酯化的人血清白蛋白（cHSA），该蛋白已被证明具有肾毒性，并与慢性肾病（CKD）患者的心力衰竭有关。通过针对cHSA的噬菌体展示，鉴定了一种特定的肽序列（cH2-p1），其对cHSA的选择性高于天然HSA。合成了cH2-p1肽，并通过等温滴定量热（ITC）分析了其靶标结合。结果表明，cH2-p1能够以不同的解离常数〜1.0×10 ^–4结合不同水平的氨基甲酸酯化的cHSA。M.该肽还显示出与氨基甲酰化纤维蛋白原（cFgn）的结合特异性，而根本不结合天然Fgn。为了更好地了解cH2-p1的结合机理，进行了cH2-p1和抗高尿胆碱与cHSA的竞争性结合，结果表明cH2-p1可以以与抗体相似的方式与高瓜氨酸残基结合。进一步进行了分子对接研究，以研究高瓜氨酸残基与cH2-p1的有利结合构象。这项工作证明了肽作为与氨基甲酰化蛋白特异性结合元件的潜力。