A Proton Water T1-NMRD Study of Ganglioside Micelles
2016 (English)In: Universal Journal of Chemistry, Vol. 4, no 2, 69-73 p.Article in journal (Refereed) Published
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=10,15,20oC). 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, τc,1 ≈ 130−160 ns, is determined by the low ﬁeld part of the NMRD proﬁle. The second correlation time, τc,2 ≈ 12 ns, is determined by the high ﬁeldpartoftheNMRDproﬁle. Theradiusoftheganglioside micelles has previously been determined as about 54 using ﬂuorescence experiments and with Stoke-Einstein relation the reorientation correlation time becomes τR= 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 withanorderparameterS6=0andτc,1 ≈ τR orcorresponding to labile protons with a τc,1as the mean life time. The proton NMRD proﬁle reveal a second Lorenzian which also can eitherbelabileandexchangingGangliosideprotonsorwater moleculesresidingintheheadgroupwithameanlifetimeas approximately 12 ns. The proton NMRD experiment cannot discriminate between these two cases.
Place, publisher, year, edition, pages
2016. Vol. 4, no 2, 69-73 p.
Proton T1.NMRD Profiels, Proton Spin-lattice Relaxation, Ganglioside Micelles
IdentifiersURN: urn:nbn:se:umu:diva-124908DOI: 10.13189/ujc.2016.040204OAI: oai:DiVA.org:umu-124908DiVA: diva2:956454