1H and 13C hyperfine coupling constants of the tryptophanyl cation radical in aqueous solution from microsecond time-resolved CIDNP.

Journal article

Relative values of the 1H and 13C isotropic hyperfine couplings in the cationic oxidized tryptophan radical TrpH*+ in aqueous solution are determined. The data are obtained from the photo-CIDNP (chemically induced dynamic nuclear polarization) enhancements observed in the microsecond time-resolved NMR spectra of the diamagnetic products of photochemical reactions in which TrpH*+ is a transient intermediate. The method is validated using the tyrosyl neutral radical Tyr*, whose 1H and 13C hyperfine couplings have previously been determined by electron paramagnetic resonance spectroscopy. Good agreement is found with hyperfine coupling constants for TrpH*+ calculated using density functional theory methods but only if water molecules are explicitly included in the calculation.

Authors: Kiryutin, A; Morozova, O; Kuhn, LT; Yurkovskaya, A; Hore, P

• Publication status: Published
• Journal: journal of physical chemistry. B
• Volume: 111
• Issue: 38
• Pages: 11221-11227
• Publication date: 2007-09-01
• DOI: 10.1021/jp073385h
• EISSN: 1520-5207
• ISSN: 1520-6106
• Language: English
• Keywords: Time Factors; Protons; Crystallography, X-Ray; Cations; Free Radicals; Tryptophan; Water; Magnetic Resonance Spectroscopy; Electric Conductivity; Viscosity; Carbon Isotopes; Solutions