title: 1H and 13C hyperfine coupling constants of the tryptophanyl cation radical in aqueous solution from microsecond time-resolved CIDNP.
abstract: 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.affiliation: International Tomography Center of SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia.
authors.forename: Alexey S
authors.initials: AS
authors.lastname: Kiryutin
authors.forename: Olga B
authors.initials: OB
authors.lastname: Morozova
authors.forename: Lars T
authors.initials: LT
authors.lastname: Kuhn
authors.forename: Alexandra V
authors.initials: AV
authors.lastname: Yurkovskaya
authors.forename: P J
authors.initials: PJ
authors.lastname: Hore
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D018360:Crystallography, X-Ray; D004553:Electric Conductivity; D005609:Free Radicals / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011522:Protons; D012996:Solutions; D013997:Time Factors; D014364:Tryptophan / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D002412:Cations; D005609:Free Radicals; D011522:Protons; D012996:Solutions; D014867:Water; D014364:Tryptophan