Molecular structures of amyloses of various plants

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The structures of amyloses from corn, rice, wheat, chestnut, kuzu, lily, nagaimo, tapioca and sweet potato were investigated in detail. The cereal amyloses were purified by the procedures involving ultracentrifugation, and the conventional autoclaving procedure was avoided, since it degraded the amyloses. There was almost no variety difference in the structures of amyloses each from rices (3 indica and 2 japonica varieties) and sweet potatoes (Koganesengan, Minamiyutaka and Norin-2 varieties). The molecular sizes of the amyloses ranged from the average degree of polymerization (d.p.) of 960 to 3280, and the cereal amyloses were smaller than the others. Most amyloses comprised 3-5 chains per molecule, but the tapioca and sweet potato amyloses had 8-10 chains. The structures of branched molecules of the amyloses were elucidated by the structural analyses of beta-limit dextrins of the amyloses. The wheat, nagaimo, lily, sweet potato and tapioca amyloses contained large branched-molecules, while the corn and chestnut amyloses had small ones. The corn, kuzu, nagaimo and lily branched-molecules had long inner chains (d.p., 150), while the chestnut and wheat amyloses had short ones (d.p., 60-91). The corn branched-molecules comprised the least 5 chains, while the wheat, tapioca and sweet potato had from 14-17 chains. The remainder had from 8-11 chains. The rice, wheat, chestnut and nagaimo amyloses contained low molar fractions (-1/3) of the branched molecules, while the sweet potato amylose had high molar fraction (-2/3). The remainder comprised nearly equal numbers of linear and branched molecules. These results indicate that the amyloses of various origins have their own characteristic structures.