Faculty Collaboration Database

Influence of intramolecular electron transfer mechanism in biological nitration, nitrosation, and oxidation of redox-sensitive amino acids. Methods Enzymol 2008;440:65-94

Date

04/22/2008

Pubmed ID

18423211

DOI

10.1016/S0076-6879(07)00804-X

Scopus ID

2-s2.0-44849111614 (requires institutional sign-in at Scopus site)   12 Citations

Abstract

Using both high-performance liquid chromatography (HPLC) and electron spin resonance (ESR) spin-trappng techniques, we developed an analytical methodology for investigating intramolecular electron transfer-mediated tyrosyl nitration and cysteine nitrosation in model peptides. Peptides N-acetyl-TyrCys-amide (YC), N-acetyl-TyrAlaCys-amide, N-acetyl-TyrAlaAlaCys-amide, and N-acetyl-TyrAlaAlaAlaAlaCys-amide were used as models. Product analysis showed that nitration and oxidation products derived from YC and related peptides in the presence of myeloperoxidase (MPO)/H(2)O(2)/NO(2)(-) were not detectable. The major product was determined to be the corresponding disulfide (e.g., YCysCysY), suggestive of a rapid electron transfer from the tyrosyl radical to the cysteinyl residue. ESR spin-trapping experiments with 5,5'-dimethyl-1-pyrroline N-oxide (DMPO) demonstrated that thiyl radical intermediates were formed from peptides (e.g., YC) treated with MPO/H(2)O(2) and MPO/H(2)O(2)/NO(2)(-). Blocking the thiol group in YC totally abrogated thiyl radical formation. Under similar conditions, we were, however, able to trap the tyrosyl radical using the spin trap dibromonitrosobenzene sulfonic acid (DBNBS). Competition spin-trapping experiments revealed that intramolecular electron transfer is the dominant mechanism for thiyl radical formation in YC peptides. We conclude that a rapid intramolecular electron transfer mechanism between redox-sensitive amino acids could influence both protein nitration and nitrosation reactions. This mechanism brings together nitrative, nitrosative, and oxidative mechanisms in free radical biology.

Author List

Zhang H, Xu Y, Joseph J, Kalyanaraman B

Author

Balaraman Kalyanaraman PhD Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acids
Animals
Electron Transport
Humans
Nitrates
Nitrosation
Oxidation-Reduction