3-Nitrotyrosine (Nit) belongs to products of oxidative stress and could probably influence conformation of neurodegenerative proteins. Syntheses of peptides require availability of suitable synthon for introduction of Nit residue. Common phenolic protection groups are more acid labile, when they are attached to Nit residue. We have found that Fmoc-Nit(Bn)-OH is a good building block for syntheses of Nit containing peptides by Fmoc/tBu strategy. Interestingly, the peptides containing multiple Nit residues can be available solely by use of Fmoc-Nit(Bn)-OH synthon. Bn is removed rapidly with ca 80 % trifluoroacetic acid in dark. The cleavage of Bn from Fmoc-Nit(Bn)-OH proceeds via pseudo-first order mechanism with activation barrier 32 kcal mol(-1) and rate k = 15.3 s(-1) at 20 °C. This rate is more than 2,000,000 times faster than that for cleavage of benzyl from Tyr(Bn).

Department of Chemistry of Natural Compounds Faculty of Food and Biochemical Technology University of Chemistry and Technology Prague Technická 5 166 28 Prague 6 Czech Republic

Institute of Organic Chemistry and Biochemistry Academy of Sciences Flemingovo náměstí 2 16610 Prague 6 Czech Republic

Amino Acids. 2019 Nov;51(10-12):1689-1690. doi: 10.1007/s00726-019-02780-9. PubMed

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Monitoring peptide tyrosine nitration by spectroscopic methods