State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen 28759, Germany.
J Am Chem Soc. 2022 Aug 24;144(33):15072-15078. doi: 10.1021/jacs.2c03923. Epub 2022 Aug 11.
Chirality is essential in nearly all biological organizations and chemical reactions but is rarely considered due to technical limitations in identifying L/D isomerization. Using OmpF, a membrane channel from with an electrostatically asymmetric constriction zone, allows discriminating chiral amino acids in a single peptide. The heterogeneous distribution of charged residues in OmpF causes a strong lateral electrostatic field at the constriction. This laterally asymmetric constriction zone forces the sidechains of the peptides to specific orientations within OmpF, causing distinct ionic current fluctuations. Using statistical analysis of the respective ionic current variations allows distinguishing the presence and position of a single amino acid with different chiralities. To explore potential applications, the disease-related peptide β-Amyloid and its d-Asp isoform and a mixture of the icatibant peptide drug (HOE 140) and its d-Ser mutant have been discriminated. Both chiral isomers were not applicable to be distinguished by mass spectroscopy approaches. These findings highlight a novel sensing mechanism for identifying single amino acids in single peptides and even for achieving single-molecule protein sequencing.
手性在几乎所有的生物组织和化学反应中都是至关重要的，但由于在识别 L/D 异构化方面存在技术限制，因此很少被考虑。使用 OmpF，一种来自 的膜通道，具有静电不对称的收缩区，允许在单个肽中区分手性氨基酸。OmpF 中带电荷残基的不均匀分布在收缩区产生强烈的侧向静电场。这个不对称的收缩区迫使肽的侧链在 OmpF 中处于特定的取向，导致离子电流的明显波动。通过对各自离子电流变化的统计分析，可以区分具有不同手性的单个氨基酸的存在和位置。为了探索潜在的应用，我们区分了与疾病相关的肽 β-淀粉样蛋白及其 d-天冬氨酸异构体，以及icatibant 肽药物 (HOE 140) 和其 d-丝氨酸突变体的混合物。这两种手性异构体都不适用于质谱方法来区分。这些发现强调了一种新的传感机制，用于识别单个肽中的单个氨基酸，甚至可以实现单分子蛋白质测序。
