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School of Biosciences. “Global” Hydrodynamic Analysis of the Molecular Flexibility of Konjac Glucomannans. Gordon Morris. Outline:. 1. Introduction 2. Hydrodynamic characterisations 3. Conformational analyses 4. Conclusions and Future Work. Introduction:.
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School of Biosciences “Global” Hydrodynamic Analysis of the Molecular Flexibility of Konjac Glucomannans Gordon Morris
Outline: 1. Introduction 2.Hydrodynamic characterisations3. Conformational analyses4. Conclusions and Future Work
Introduction: Why characterisation of Konjac glucomannan (KGM) is important - Widely used but poorly understood health food supplement - Reported potential interaction with wheat gliadins: application in gluten removal - Biopolymer of interest in diabetes research
KGM: 1. Extracted from the tubers of Amorphophullus Konjac C. Koch 2. Water-soluble gum3.b-(14) b-D-glucose (G) and b-D-mannose (M) - G:M ratio 1:1.6 - C-6 acetylation (5 – 10 %)
Hydrodynamic characterisations: Sedimentation Velocity in the Analytical Ultracentrifuge - sedimentation coefficient, s020,w - concentration dependence of sedimentation, ksSize Exclusion Chromatography coupled to Multi-Angle Laser Light Scattering - weight average molar mass, MwViscometry - intrinsic viscosity, [h]
Conformational analyses: 1.Sedimentation conformation zoning2.Bushin-Bohdanecky approach3. Yamakawa-Fujii approach4. Combined “global” analysis: HYDFIT5. Mark-Houwink-Kuhn-Sakurada (MHKS) relation6. Wales-van Holde & frictional ratios
Sedimentation Conformation Zoning: Extra rigid rod e.g. schizophyllan Rigid rod e.g. xanthan KGM: semi-flexible coil Semi-flexible coil e.g. pectin Random coil e.g. pullulan Globular e.g. glycogen Pavlov et al. (1997). Trends in Analytical Chemistry, 16, 401-405.
Bushin-Bohdanecky: • Lp ~ 8 nm • Semi-flexible coil Bohdanecky (1983). Macromolecules, 16, 1483-1493. Bushin et al., (1981). Vysokomolekulyarnye Soedineniya, A23, 2494-2503.
Yamakawa-Fujii: • Lp ~ 33 nm • Rigid rod Yamakawa & Fujii (1973). Macromolecules, 6, 407-405.
HYDFIT: D • Lp ~ 13 nm • ML ~ 330 g mol-1 nm-1 • Semi-flexible coil Ortega & García de la Torre (2007). Biomacromolecules, 8, 2464-2475.
Conclusions1. Discrepancy between Bushin-Bohdanecky and Yamakawa-Fujii approaches - best to use non-biased HYDFIT method2. Konjac glucomannan has a semi-flexible coil conformationFuture Work1. Characterisation of KGM-gliadin complexes2. Investigation of KGM-insulin mixtures
Acknowledgements: Prof. Stephen E. Harding & Ali Saber Abdelhameed, University of Nottingham, UK Dr. M. Samil Kök, University of Bolu, TurkeyDr. Jose Garcìa de la Torre & Dr. Alvaro Ortega, University of Murcia, Spain