This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Structures of a number of biologically important and industrially useful polysaccharides will be determined using the fiber diffraction data obtained from oriented specimens. Our long-term goals are to determine the three-dimensional structures for explaining the molecular basis of the functional behavior of biopolymers. Polysaccharides for ongoing structural investigation are of algal (iota-carrageenan, kappa-carrageenan and lambda-carrageenan), bacterial (cepacian and gellan analog), plant (rhamnogalacturonan, succinoglucan) origins and mixed systems such as bacterial acetan:plant glucomannan & xanthan:glucomannan in various monovalent and divalent cation forms. Since these molecules or molecular complexes tend to form helical structures with very limited lateral ordering, they can at best be prepared as polycrystalline and well oriented specimens. Hence, fiber diffraction is the only method of choice for visualizing their three-dimensional structures. Such atomic details are helpful in understanding their interactions with solvent and solute molecules and with other polysaccharides for effective utilization. Oriented and polycrystalline fibers will be obtained from aqueous polymer solutions through stretching process at room temperature. Some of the fibers have already provided promising patterns at the BioCAT Synchrotron facilities at ANL in the past year. Linked-Atom Least-Squares (LALS) program will be used to build molecular models in conformity with the diffraction pattern and solve the structures.
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