Phosphorylation is among the most widely distributed mechanisms regulating the tunable structure and function of proteins in response to neuronal, hormonal and environmental signals. We demonstrate here that the low-voltage electrochemical reduction of histidine residues in reflectin A1, a protein that mediates the neuronal fine-tuning of colour reflected from skin cells for camouflage and communication in squids, acts as an in vitro surrogate for phosphorylation in vivo, driving the assembly previously shown to regulate its function. Using micro-drop voltammetry and a newly designed electrochemical cell integrated with an instrument measuring dynamic light scattering, we demonstrate selective reduction of the imidazolium side chains of histidine in monomers, oligopeptides and this complex protein in solution. The formal reduction potential of imidazolium proves readily distinguishable from those of hydronium and primary amines, allowing unequivocal confirmation of the direct and energetically selective deprotonation of histidine in the protein. The resulting ‘electro-assembly’ provides a new approach to probe, understand, and control the mechanisms that dynamically tune protein structure and function in normal physiology and disease. With its abilities to serve as a surrogate for phosphorylation and other mechanisms of charge neutralization, and to potentially isolate early intermediates in protein assembly, this method may be useful for analysing never-before-seen early intermediates in the phosphorylation-driven assembly of other proteins in normal physiology and disease.

中文翻译：

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电化学作为蛋白质磷酸化的替代物：反射蛋白 A1 的电压控制组装

磷酸化是最广泛分布的机制之一，可调节蛋白质响应神经元、激素和环境信号的可调结构和功能。我们在这里证明了反射蛋白 A1 中组氨酸残基的低压电化学还原，反射蛋白 A1 是一种蛋白质，介导从皮肤细胞反射的颜色的神经元微调，用于鱿鱼的伪装和交流，作为体内磷酸化的体外替代物，驱动先前显示的组件以调节其功能。使用微滴伏安法和新设计的电化学电池与测量动态光散射的仪器集成，我们证明了单体、寡肽和溶液中这种复杂蛋白质中组氨酸的咪唑侧链的选择性还原。咪唑鎓的正式还原电位证明很容易与水合氢和伯胺的还原电位区分开来，从而明确确认蛋白质中组氨酸的直接和能量选择性去质子化。由此产生的“电组装”提供了一种新的方法来探测、理解和控制在正常生理和疾病中动态调节蛋白质结构和功能的机制。由于它能够作为磷酸化和其他电荷中和机制的替代物，并有可能分离蛋白质组装中的早期中间体，这种方法可能有助于分析其他蛋白质磷酸化驱动组装中前所未见的早期中间体在正常的生理和疾病中。