Electrocatalytic oxidation of tyrosines shows signal enhancement in label-free protein biosensors

Wei, Ming-Yuan; Famouri, Parviz; Guo, Liang-Hong

doi:10.1016/j.trac.2012.07.003

Cited by 24 publications

(12 citation statements)

References 180 publications

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“…These analytical figures of merit compare favorably with prior reports relevant to the two amino acids. 25 In contrast to glucagon, the linear range for the determination of free tryptophan and tyrosine was wider and extended to at least 10 μM (R 2 = 0.999).…”

Section: Resultsmentioning

confidence: 98%

Hormone glucagon: electrooxidation and determination at carbon nanotubes

Karra

Griffith

Kennedy

et al. 2016

Analyst

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The oxidation of glucagon, which is one of the key hormones in glucose homeostasis, was studied at electrodes modified with carbon nanotubes (CNT) that were dispersed in a polysaccharide adhesive chitosan (CHIT). Such electrodes displayed improved resistance to fouling, which allowed for the investigation of both the electrolysis/mass spectrometry and electroanalysis of glucagon. The off-line electrospray ionization and tandem mass spectrometric analyses showed that the -4 Da mass change to glucagon upon electrolysis at CNT was due to the electrooxidation of its tryptophan (W25) and dityrosine (Y10, Y13) residues. The methionine residue of glucagon did not contribute to its oxidation. The amperometric determination of glucagon yielded the limit of detection equal to ~20 nM (E = 0.800 V, pH 7.40, S/N = 3), sensitivity of 0.46 A M−1 cm−2, linear dynamic range up to 2.0 μM (R2 = 0.998), response time <5 s, and good signal stability. Free tryptophan and tyrosine yielded comparable analytical figures of merit. The direct amperometric determination of unlabeled glucagon at CHIT-CNT electrodes is the first example of a rapid alternative to the complex analytical assays of this peptide.

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Section: Resultsmentioning

confidence: 98%

Hormone glucagon: electrooxidation and determination at carbon nanotubes

Karra

Griffith

Kennedy

et al. 2016

Analyst

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“…This oxidation peak, that sequentially decreased as a function of the number of sweeping cycles has been attributed to the irreversible oxidation of three amino acids (cysteine, tryptophan and tyrosine) that, after protein adsorption, are in close proximity to the electrode surface [39, 40] and could, in some extreme cases, lead to cleavage events [41]. Considering these peak potentials, the results described support the hypothesis that the oxidation process observed at positive potentials is related to the amino acids and is clearly decoupled from the redox activity of the FADH 2 (present in the active site).…”

Section: Resultsmentioning

confidence: 99%

Adsorption and catalytic activity of glucose oxidase accumulated on OTCE upon the application of external potential

Benavidez¹,

Torrente²,

Marucho³

et al. 2014

Journal of Colloid and Interface Science

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This article describes the adsorption of glucose oxidase (GOx) onto optically transparent carbon electrodes (OTCE) under the effect of applied potential and the analysis of the enzymatic activity of the resulting GOx/OTCE substrates. In order to avoid electrochemical interferences with the enzyme redox center, control electrochemical experiments were performed using flavin adenine dinucleotide (FAD) and GOx/OTCE substrates. Then, the enzyme adsorption experiments were carried out as a function of the potential applied (ranged from the open circuit potential to +950 mV), the pH solution, the concentration of enzyme, and the ionic strength on the environment. The experimental results demonstrated that an increase in the adsorbed amount of GOx on the OTCE can be achieved when the potential was applied. Although the increase in the adsorbed amount was examined as a function of the potential, a maximum enzymatic activity was observed in the GOx/OTCE substrate achieved at +800 mV. These experiments suggest that although an increase in the amount of enzyme adsorbed can be obtained by the application of an external potential to the electrode, the magnitude of such potential can produce detrimental effects in the conformation of the adsorbed protein and should be carefully considered. As such, the article describes a simple and rational approach to increase the amount of enzyme adsorbed on a surface and can be applied to improve the sensitivity of a variety of biosensors.

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“… 190 Different methods have been developed for studies of kinase-catalyzed protein phosphorylation (e.g., refs ( 191 − 193 )), including relatively simple and inexpensive EC methods. 164 , 185 , 186 , 194 − 200 First papers showed that phosphorylation of peptides and proteins resulted in a decrease of Tyr oxidation peak using screen-printed electrode. 164 , 201 The difference between oxidation peaks of phosphorylated and nonphosphorylated Tyr was recently used by Li et al 202 to investigate activity and inhibition of protein kinase at a graphene-modified GCE.…”

Section: Protein Oxidation At Carbon and Other Solid Electrodesmentioning

confidence: 99%