Zein, purified from maize inbred W64A, was chromatographed on a column of hydroxypropylated Sephadex G-100 equilibrated with 75% ethanol containing 0·01 M HCI. The fractions obtained were examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate or acid-urea before and after reduction of disulfide bonds. Mr 22,000 polypeptides, free of Mr 24,000 polypeptides, were isolated from the proteins that were eluted last and were compared with total zein by two-dimensional electrophoresis consisting of isoelectric focusing in the first dimension and acid-urea gel electrophoresis in the second. The Mr 22,000 fraction consisted of at least nineteen proteins exhibiting microheterogeneity. These data indicate that zein comprises two sets of closely related polypeptides that exist free or as oligomers, mainly dimers.

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