Argos P, Pedersen K, Marks M D, Larkins B A
J Biol Chem. 1982 Sep 10;257(17):9984-90.
With the knowledge of the amino acid sequences of two maize zein proteins (apparent molecular weights of 19,000 and 22,000), a structural model is proposed for their molecular conformation. The circular dichroic spectrum taken in the 190-240 nm range for a zein protein mixture in methanol solution showed the zein secondary structure to be largely helical. The polar, hydrophobic, and turn characteristics of the zein residues, as well as the homologous repeat units in their primary sequences, suggested a structure with nine adjacent, topologically antiparallel helices clustered within a distorted cylinder. Polar residues distributed along the helical surfaces allowed intra- and intermolecular hydrogen bonding such that the zein molecules could be arranged in planes. The proposed glutamine-rich turns located between the helices and at the cylindrical caps would favor side chain interactions resulting in stacking of the molecular planes. Physical properties observed for the zein proteins are explained by the model.
基于两种玉米醇溶蛋白（表观分子量分别为19,000和22,000）的氨基酸序列信息，提出了它们分子构象的结构模型。在甲醇溶液中对玉米醇溶蛋白混合物在190 - 240 nm范围内进行的圆二色光谱显示，玉米醇溶蛋白的二级结构主要为螺旋结构。玉米醇溶蛋白残基的极性、疏水性和转角特性，以及它们一级序列中的同源重复单元，表明其结构为九个相邻的、拓扑反平行的螺旋聚集在一个扭曲的圆柱体内。沿螺旋表面分布的极性残基允许分子内和分子间形成氢键，从而使玉米醇溶蛋白分子能够排列成平面。所提出的位于螺旋之间和圆柱帽处的富含谷氨酰胺的转角有利于侧链相互作用，导致分子平面的堆积。该模型解释了观察到的玉米醇溶蛋白的物理性质。
