title: Solution-state dynamics of sugar-connected spin probes in sucrose solution as studied by multiband (L-, X-, and W-band) electron paramagnetic resonance.
abstract: A multiband (L-band, 0.7GHz; X-band, 9.4GHz; and W-band, 94GHz) electron paramagnetic resonance (EPR) study was performed for two glycosidated spin probes, 4-(alpha,beta-D-glucopyranosyloxy)-TEMPO (Glc-TEMPO) and 4-(alpha,beta-D-lactopyranosyloxy)-TEMPO (Lac-TEMPO), and one non-glycosylated spin probe, 4-hydroxy-TEMPO (TEMPOL), where TEMPO=2,2,6,6-tetramethyl-1-piperidinyloxyl, to characterize fundamental hydrodynamic properties of sugar-connected spin probes. The linewidths of these spin probes were investigated in various concentrations of sucrose solutions (0-50wt%). The multiband approach has allowed full characterization of the linewidth parameters, providing insights into the molecular shapes of the spin probes in sucrose solution. The analysis based on the fast-motional linewidth theory has yielded anisotropy parameters of rho(x) approximately 2.6 and rho(y) approximately 0.9 for Glc-TEMPO, and rho(x) approximately 4.2 and rho(y) approximately 0.9 for Lac-TEMPO. These values indicate that the glycosidated spin probes have a prolate-type molecular shape elongated along the x-axis (NO(rad) axis) with Lac-TEMPO elongated more remarkably, consistent with their molecular structures. The interaction parameters k (the ratios of the effective hydrodynamic volumes to the real ones) corrected for the difference in molecular shape have been estimated and found to have the relation k(TEMPOL)<k(Glc-TEMPO) approximately k(Lac-TEMPO). This agrees with the expectation that glycosidated spin probes can have stronger hydrogen bonding to water. Glycosidated spin probes are expected to be useful for probing sugar-involving interactions, which commonly occur in biological systems. Thus this study will provide an indispensable basis for such spin-probe studies.
authors.affiliation: Regional Joint Research Project of Yamagata Prefecture, Yamagata Public Corporation for the Development of Industry, Matsuei 2-2-1, 990-2473 Yamagata, Japan. fukui@ckk.ymgt-techno.or.jp
authors.forename: Kôichi
authors.initials: K
authors.lastname: Fukui
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ito
authors.forename: Mika
authors.initials: M
authors.lastname: Tada
authors.forename: Masaaki
authors.initials: M
authors.lastname: Aoyama
authors.forename: Shingo
authors.initials: S
authors.lastname: Sato
authors.forename: Jun ichi
authors.initials: Ji
authors.lastname: Onodera
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ohya
mesh_terms: D016880:Anisotropy; D003198:Computer Simulation; D003497:Cyclic N-Oxides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D008872:Microwaves; D008958:Models, Molecular; D008968:Molecular Conformation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry*; D013113:Spin Labels / Q000138:chemical synthesis; D013395:Sucrose / Q000737:chemistry*
chemical_list: D003497:Cyclic N-Oxides; D012996:Solutions; D013113:Spin Labels; D013395:Sucrose; C003959:TEMPO