Cereal Chem 60:342 - 344. | VIEW
Conformation of Corn Zein and Glutelin Fractions with Unusual Amino Acid Sequence.
Y. V. Wu, J. W. Paulis, K. R. Sexson, and J. S. Wall. Copyright 1983 by the American Association of Cereal Chemists, Inc.
The conformations of zein, reduced zein, alcohol-soluble reduced glutelin (ASG), water-soluble ASG, and water-insoluble ASG in 70% ethanol-0.5% sodium acetate (with and without mercaptoethanol) were studied by optical rotatory dispersion from 600 to 260 nm and circular dichroism from 240 to 204 nm. Zein has 45% alpha-helix in 70% ethanol and almost the same alpha-helical content when disulfide bonds are broken. The alpha-helical contents of water-soluble ASG and water-insoluble ASG in 70% ethanol-0.1M mercaptoethanol are near 25%, but ASG has 51% alpha-helix. The water-soluble ASG has 25 mole percent proline and a -Pro-Pro-Pro-Val-His-Leu- sequence tandemly repeated six to eight times near the N-terminal. Apparently, the portion of water-soluble ASG that is relatively less rich in proline allows alpha-helix formation.