For use in the voltammetric sensing of galactose-dependent proteins, we modified magnetic beads with a peptide that had both electroactive- and molecular recognition properties. The peptide consisted of a YXY sequence and behaved as an electron-transfer carbohydrate-mimetic peptide that would combine with proteins. With this tool, the protein could be detected via a label-free system. We synthesized several penta- and hexa-peptides with a cysteine residue on the C-terminals to examine the properties of peptides. These peptides contained amino acid residues (X) of alanine, serine, or tyrosine. The peptides were immobilized on magnetic beads via N-(8-maleimidocapryloxy) succinimide. Soybean agglutinin(SBA), the in vivo function of which has been well established in animals, was selected as a model protein. The protein was detected via the changes in electrode response due to the oxidation of tyrosine residues from the phenol group to quinone. As a result, SBA was selectively accumulated on the beads modified with YYYYC. The calibration curve of SBA was linear and ranged from 2.5 × 10-12 to 1.0 × 10-10 M. With this system, SBA was recovered in human serum at values that ranged from 98 to 103%. Furthermore, the beads with peptides were regenerated five times using a protein denaturant. Accordingly, this electrochemical system was simple and could be rapidly applied to the detection of galactose-recognition proteins.

中文翻译：

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用电子转移碳水化合物模拟肽修饰的磁珠用于检测半乳糖依赖性蛋白质

为了用于半乳糖依赖性蛋白质的伏安传感，我们用具有电活性和分子识别特性的肽修饰了磁珠。该肽由 YXY 序列组成，表现为电子转移碳水化合物模拟肽，可与蛋白质结合。使用此工具，可以通过无标记系统检测蛋白质。我们合成了几种在 C 端具有半胱氨酸残基的五肽和六肽，以检查肽的特性。这些肽含有丙氨酸、丝氨酸或酪氨酸的氨基酸残基 (X)。肽通过 N-(8-maleimidocapryloxy) 琥珀酰亚胺固定在磁珠上。大豆凝集素(SBA) 的体内功能已在动物中得到很好的证实，被选为模型蛋白。由于酪氨酸残基从苯酚基团氧化为醌，因此通过电极响应的变化来检测蛋白质。结果，SBA 选择性地积聚在用 YYYY 修饰的珠子上。SBA 的校准曲线呈线性，范围为 2.5 × 10-12 至 1.0 × 10-10 M。使用该系统，SBA 在人血清中的回收率范围为 98% 至 103%。此外，使用蛋白质变性剂将带有肽的珠子再生五次。因此，该电化学系统简单，可快速应用于半乳糖识别蛋白的检测。5 × 10-12 至 1.0 × 10-10 M。使用该系统，SBA 在人血清中的回收率范围为 98% 至 103%。此外，使用蛋白质变性剂将带有肽的珠子再生五次。因此，该电化学系统简单，可快速应用于半乳糖识别蛋白的检测。5 × 10-12 至 1.0 × 10-10 M。使用该系统，SBA 在人血清中的回收率范围为 98% 至 103%。此外，使用蛋白质变性剂将带有肽的珠子再生五次。因此，该电化学系统简单，可快速应用于半乳糖识别蛋白的检测。