Boron-Doped Diamond Electrodes for the Electrochemical Oxidation and Cleavage of Peptides
作者:Julien Roeser、Niels F. A. Alting、Hjalmar P. Permentier、Andries P. Bruins、Rainer Bischoff
DOI:10.1021/ac303795c
日期:2013.7.16
Electrochemical oxidation of peptides and proteins is traditionally performed on carbon-based electrodes. Adsorption caused by the affinity of hydrophobic and aromatic amino acids toward these surfaces leads to electrode fouling. We compared the performance of boron-doped diamond (BDD) and glassy carbon (GC) electrodes for the electrochemical oxidation and cleavage of peptides. An optimal working potential of 2000 mV was chosen to ensure oxidation of peptides on BDD by electron transfer processes only. Oxidation by electrogenerated OH radicals took place above 2500 mV on BDD, which is undesirable if cleavage of a peptide is to be achieved. BDD showed improved cleavage yield and reduced adsorption for a set of small peptides, some of which had been previously shown to undergo electrochemical cleavage C-terminal to tyrosine (Tyr) and tryptophan (Trp) on porous carbon electrodes. Repeated oxidation with BDD electrodes resulted in progressively lower conversion yields due to a change in surface termination. Cathodic pretreatment of BDD at a negative potential in an acidic environment successfully regenerated the electrode surface and allowed for repeatable reactions over extended periods of time. BDD electrodes are a promising alternative to GC electrodes in terms of reduced adsorption and fouling and the possibility to regenerate them for consistent high-yield electrochemical cleavage of peptides. The fact that OH-radicals can be produced by anodic oxidation of water at elevated positive potentials is an additional advantage as they allow another set of oxidative reactions in analogy to the Fenton reaction, thus widening the scope of electrochemistry in protein and peptide chemistry and analytics.
肽和蛋白质的电化学氧化传统上是在基于碳的电极上进行的。疏水性和芳香族氨基酸对这些表面的亲和力导致了电极的污垢沉积。我们比较了掺硼金刚石(BDD)和玻璃碳(GC)电极在肽的电化学氧化和裂解中的性能。选择了2000 mV的最佳工作电位,以确保在BDD上仅通过电子传递过程进行肽的氧化。在BDD上,2500 mV以上的电位下发生了由电发生的OH自由基引起的氧化,这在需要裂解肽时是不可取的。对于一组小肽,BDD显示了更高的裂解产率和减少的吸附作用,其中一些肽之前在多孔碳电极上被证明能在酪氨酸(Tyr)和色氨酸(Trp)的C末端进行电化学裂解。使用BDD电极重复氧化导致转换产率逐渐降低,这是由于表面终止的变化。在酸性环境中以负电位对BDD进行阴极预处理成功再生了电极表面,并允许在较长时间内进行可重复的反应。相较于GC电极,BDD电极在减少吸附和污垢以及再生的可能性方面是一个很有前景的替代方案,从而实现了一致的高产率的肽电化学裂解。水在较高正电位下的阳极氧化可以产生OH自由基这一额外优势,使其与芬顿反应中的另一组氧化反应相类似,从而扩大了电化学在蛋白质和肽化学及分析中的应用范围。