33A-5 |
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M. BENMOUSSA, J. A. Gray, X. Z. Han, J. N. BeMiller, and B. R. Hamaker. Whistler Center for Carbohydrate Research, Purdue Univ., Dept. of Food Science, 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009 The presence of starch granule channels has been previously reported. It has been hypothesized and shown in concept that corn and sorghum genotypes containing more channels are likewise more susceptible to amylase digestion. This may have implications in the animal feed industry as higher utilization of grain translates to higher feed efficiency and lower cost of feeding. Our objective was to identify starch granule channel proteins and their potential role in digestibility. Waxy maize and sorghum starch granule proteins labeled with protein specific dye that is only fluorescent in the presence of primary amines (CBQCA) were examined using confocal laser scanning microscopy (CLSM). Upon incubation with added thermolysin protease enzyme, proteins were apparently removed by evidence of no noticeable signal from channel surfaces. Apparently, differences in density of channels between different starch varieties exist which can be seen by CLSM. Protein extracts from purified starch granules were analyzed by SDS-PAGE using 18-10 gradient gels and visualized by staining with Coomassie Blue. Protein gels showed the presence of proteins with different molecular weight ranging between 10 to 44 kDa. N-terminal sequencing of one of the major starch granule surface protein with molecular weight 40kDa showed a sequence matching with brittle 1. This channel protein may have transporter characteristics.
Session 33A, Carbohydrate: General
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