Conformational and spectroscopic analysis of the tyrosyl radical dipeptide analogue in the gas phase and in aqueous solution by a density functional/continuum solvent model.
The conformational and spectroscopic properties of the tyrosyl radical dipeptide analogue (T(R)DA) are investigated both in gas phase and in aqueous solution by means of density functional calculations. Electronic interactions between backbone and side chain, determining the relative stability of the different energy minimums, depend on the electronic state of the phenoxy substituent. As a consequence, (i) the conformational behavior of T(R)DA is quite different from that of the tyrosine dipeptide analogue, and (ii) the energy required for the homolytic breaking of the OH bond depends on the adopted conformation. The calculated hyperfine coupling constants are in good agreement with the available experimental results. Side-chain-backbone interactions cause an asymmetrization of the magnetic properties of the phenoxy ring and deviations from McConnell relationship. Solvent effects, taken into account by means of a combined discrete/continuum model, significantly affect both the conformational and the magnetic behavior of T(R)DA.
Langella
Emma
E
Dipartimento di Chimica, Università Federico II, via Cintia, I-80126 Napoli, Italy.
Improta
Roberto
R
Barone
Vincenzo
V
D004151:Dipeptides / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D008958:Models, Molecular; D011487:Protein Conformation; D012996:Solutions; D013816:Thermodynamics; D014443:Tyrosine / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D004151:Dipeptides; D005609:Free Radicals; D012996:Solutions; D014867:Water; D014443:Tyrosine