Journals Information
Universal Journal of Chemistry(CEASE PUBLICATION) Vol. 4(2), pp. 69 - 73
DOI: 10.13189/ujc.2016.040204
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A Proton Water T1 -NMRD Study of Ganglioside Micelles
Per-Olof Westlund *
Department of Chemistry, Umea University, Sweden
ABSTRACT
Ganglioside GM1 (GM1) micelles have been studied by means of water proton T1 NMRD experiment. The field dependent spin-lattice relaxation rates were measured for Larmor frequencies ranging from 0.1 to 40 MHz and for two micelle concentrations at three temperatures (T=10,15,20℃). The proton T1 NMRD-profiles are well described by assuming two proton pools are responsible for the dispersion curves. The proton pools are characterized by an effective correlation time and a proton fraction. The largest correlation time, Tc,1 ≈ 130-160 ns, is determined by the low field part of the NMRD profile. The second correlation time, Tc,2 ≈12 ns, is determined by the high field part of the NMRD profile. The radius of the ganglioside micelles has previously been determined as about 54 using fluorescence experiments and with Stoke-Einstein relation the reorientation correlation time becomes TR= 120-165 ns depending on the temperature dependence of the water viscosity. It is thus plausible to identify one pool of waterprotons, characterized by the largest effective correlation time, as corresponding to waters residing in the headgroup with an order parameter S≠0 and Tc,1 ≈ TR or corresponding to labile protons with a Tc,1 as the mean life time. The proton NMRD profile reveal a second Lorenzian which also can either be labile and exchanging Ganglioside protons or water molecules residing in the head group with a mean life time as approximately 12 ns. The proton NMRD experiment cannot discriminate between these two cases.
KEYWORDS
Proton T1.NMRD Profiles, Proton Spin-lattice Relaxation, Ganglioside Micelles
Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Per-Olof Westlund , "A Proton Water T1 -NMRD Study of Ganglioside Micelles," Universal Journal of Chemistry(CEASE PUBLICATION), Vol. 4, No. 2, pp. 69 - 73, 2016. DOI: 10.13189/ujc.2016.040204.
(b). APA Format:
Per-Olof Westlund (2016). A Proton Water T1 -NMRD Study of Ganglioside Micelles. Universal Journal of Chemistry(CEASE PUBLICATION), 4(2), 69 - 73. DOI: 10.13189/ujc.2016.040204.