Abstract
Oxidative stress may cause extended tyrosine posttranslational modifications of peptides and proteins. The 3-nitro-L-tyrosine (Nit), which is typically formed, affects protein behavior during neurodegenerative processes, such as Alzheimer’s and Parkinson’s diseases. Such metabolic products may be conveniently detected at very low concentrations by surface enhanced Raman spectroscopy (SERS). Previously, we have explored the SERS detection of the Nit NO2 bending vibrational bands in a presence of hydrogen chloride (Niederhafner et al., Amino Acids 53:517–532, 2021, ibid). In this article, we describe performance of a new SERS substrate, “pink silver”, synthesized photochemically. It provides SERS even without the HCl induction, and the acid further decreases the detection limit about 9 times. Strong SERS bands were observed in the asymmetric (1550–1475 cm−1) and symmetric (1360–1290 cm−1) NO stretching in the NO2 group. The bending vibration was relatively weak, but appeared stronger when HCl was added. The band assignments were supported by density functional theory modeling.
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Abbreviations
- ACN:
-
Acetonitrile
- Bn:
-
Benzyl
- CCT:
-
Cartesian coordinate-based tensor transfer method
- DIC:
-
N,N′-Diisopropylcarbodiimide
- DMF:
-
N,N-Dimethylformamide
- EDT:
-
1,2-Ethanedithiol
- ESI:
-
Electrospray ionization
- Fmoc:
-
9-Fluorenylmethoxycarbonyl
- GSH:
-
Glutathione
- HOBt:
-
N-Hydroxybenzotriazole
- HPLC:
-
High-performance liquid chromatography
- MD:
-
Molecular dynamics
- MS:
-
Mass spectrometry
- Nit:
-
3-Nitro-L-tyrosine
- PTM:
-
Posttranslational modification
- ROA:
-
Raman optical activity
- SERS:
-
Surface-enhanced Raman spectroscopy
- tBu:
-
Tert-Butyl
- TEM:
-
Transmission electron microscopy
- TFA:
-
Trifluoroacetic acid
- TIS:
-
Triisopropyl silane
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Acknowledgements
This work was supported by the Czech Science Foundation (22-04669S), Research Project RVO 61388963, by European Regional Development Fund; OP RDE; Project: “Chemical biology for drugging undruggable targets (ChemBioDrug)” (No. CZ.02.1.01/0.0/0.0/16_019/0000729). Computational resources were supplied by the project “e-Infrastruktura CZ” (e-INFRA CZ LM2018140) supported by the Ministry of Education, Youth and Sports of the Czech Republic. MT and JŠ thank for support from ORLEN Unipetrol Foundation provided to Mensa Gymnázium. Also, we thank Dr. Jan Ježek, Ph. D. for the corrections of English language. The molecular structures were visualized using program UCSF Chimera (Pettersen et al. 2004).
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Sokolová, M., Šestáková, H., Truksa, M. et al. Photochemical synthesis of pink silver and its use for monitoring peptide nitration via surface enhanced Raman spectroscopy (SERS). Amino Acids 54, 1261–1274 (2022). https://doi.org/10.1007/s00726-022-03178-w
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DOI: https://doi.org/10.1007/s00726-022-03178-w