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Titolo:
The intramolecular sulfur-nitrogen bond in aqueous 3-(methylthio)propylamine radical cation
Autore:
Tripathi, GNR; Tobien, T;
Indirizzi:
Univ Notre Dame, Radiat Lab, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 iat Lab, Notre Dame, IN 46556 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY A
fascicolo: 14, volume: 105, anno: 2001,
pagine: 3498 - 3504
SICI:
1089-5639(20010412)105:14<3498:TISBIA>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
RESOLVED RESONANCE RAMAN; ELECTRON-SPIN-RESONANCE; CONTAINING AMINO-ACIDS; 4-CARBOXYBENZOPHENONE-SENSITIZED PHOTOOXIDATION; SENSITIZED PHOTOOXIDATION; 3-ELECTRON BONDS; S-N; METHIONINE; SPECTRA; SPECTROSCOPY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Tripathi, GNR Univ Notre Dame, Radiat Lab, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 Dame, IN 46556 USA
Citazione:
G.N.R. Tripathi e T. Tobien, "The intramolecular sulfur-nitrogen bond in aqueous 3-(methylthio)propylamine radical cation", J PHYS CH A, 105(14), 2001, pp. 3498-3504

Abstract

Kinetic and structural properties of the intramolecular sulfur-nitrogen bond (>S therefore NH2+.-) in aqueous 3-(methylthio)propylamine (3-MTPA) radical cation have been examined as a model for the cyclized radical state of L-methionine, an essential aminoacid in protein biosynthesis. The (OH)-O-. radical reacts with amine-protonated 3-MTPA at a rate constant of 8.3 x 10(9) M-1 s(1), primarily by addition at the sulfur site. Intramolecular hydrogen abstraction and water elimination from the (OH)-O-. adduct (3-MTPAH(+)-OH. --> 3-MTPA(+.) + H2O) occurs at a rate of 9.4 x 10(7) s(-1), forming the radical cation. The Raman scattering of 3-MTPA(+.), excited in resonance with its broad 390-nm absorption on the microsecond times, exhibits a surprisingly simple spectrum dominated by a strongly enhanced S thereforeN stretching vibration at 288 cm(-1), observed for the first time. This observation provides vibrational spectroscopic evidence of intramolecular bonding in 3-MTPA(+.) and shows that the 390-nm absorption of the radical is almost completely confined to the S thereforeN bond. The equilibrium S-N separation in the radical is estimated as similar to2.5 Angstrom. The hypothetical intermediate, SNOH., presumed to be formed on oxidation of methionine and derivatives in basic solutions, has been identified with the > S therefore NH.-species.

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Documento generato il 20/09/20 alle ore 06:40:14