Naslov
Temperature Dependence of the structure of the first stable L-alanine radical: An ENDOR study

Autori
Rakvin, Boris ; Maltar-Strmečki, Nadica ; Kattnig, Daniel ; Grampp, Günter

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
The 40th Annual International Meeting Electron Spin Resonance Group Royal Society of Chemistry & COST P15 action on &#8220 ; Advanced Paramagnetic Resonance Methods in Molecular Biophysics&#8221 ; ; Oxford / - , 2007, 118-118

Skup
The 40th Annual International Meeting Electron Spin Resonance Group Royal Society of Chemistry & COST P15 action on &#8220 ; ; Advanced Paramagnetic Resonance Methods in Molecular Biophysics&#8221 ; ;

Mjesto i datum
Oxford, Ujedinjeno Kraljevstvo, 25.03.2007. - 29.03.2007

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
L-alanin; ENDOR; radikali
(L-alanine; ENDOR; radicals)

Sažetak
The first stable L-alanine radical, • CHCH3COOH, henceforth, SAR1, has been studied over many years and remains the most highly studied paramagnetic center of a simple amino acid in the solid form. It has been examined by various electron paramagnetic resonance techniques (ESR, FT ESR, ENDOR, ELDOR). Despite of these investigations, molecular environment of the radical regarding the unusual large shift of the central carbon atom, Cα , containing 0.75 unpaired spin density as well as the dynamic processes associated with the radical motion are still not fully understood. Theoretical modelling of SAR1 center was found restricted only on the center itself without any interaction with surrounding atoms. Moreover, internal rotations of the CH3 and NH3 + groups accompanied with molecular zwitterionic form in the crystalline state produce even more complex local environment of SAR1 for theoretical description at room temperature. Thus, for complete descriptions of the center one expects that additional improvement on more accurate estimation of the local position of the center and on more detailed evaluation of dynamical properties are essentials. The ENDOR study of α -proton linewidth and line intensities as well as hyperfine coupling of SAR1 as a function of temperature was undertaken in order to bring new experimental parameters for additional more detailed description of SAR1 dynamics. Temperature dependence of the α -proton hyperfine coupling constants for the magnetic field parallel to the a, b, and c axes are measured in the temperature interval 200-325 K. The obtained results are interpreted in terms of statistical average of the stable and unstable radical structures. Presented results are in accord with earlier ESR measurement of α -proton splitting at significantly higher temperatures (289 - 423 K). The ENDOR data clearly confirmed presence of additional dynamic properties of SAR1 center at room temperature besides well known internal rotation of CH3 group.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija

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