STRUCTURAL DETERMINATIONS OF PROLAMINES FROM RICE

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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. Prolamines are one of the major types of storage proteins found in seeds and thus are a dietary source of protein from grains. The prolamines are retained in the ER lumen and are assembled into intracisternal inclusion granules. They are rich in proline and glutamine. The storage proteins serve as a nitrogen source for the developing plant embryo and also play a role in human nutrition. It is possible that the storage proteins may be implicated in food allergies. Prolamines in some plants are involved in Celiac Disease. While this is not the case in rice, their thorough investigation is also warranted in this organism. Several prolamines from rice have been purified and their structures are being determined. One aspect being investigated is the possibe occurrence of of glycosylation. The prolamines from rice were separated by HPLC, and the two major fractions have been investigated by mass spectrometry. In both fractions, a major component could be characterized and partally sequenced by MALDI TOF MS, and by tandem nanospray MS on triple quadrupole, QoTOF, and FT-ICR mass spectrometers. Further analysis by FT-ICR MS should also allow for the characterization of the minor components. Western blots have recently provided some evidence that a component in the mixture has O-linked modifications, including possibly O-GlcNAc..