Rani Monika, Sogi Dalbir Singh, Gill Balmeet Singh
Department of Food Science and Technology, Guru Nanak Dev University, Amritsar, Punjab, India.
Sci Rep. 2021 Nov 30;11(1):23135. doi: 10.1038/s41598-021-02099-0.
Prolamins, alcohol soluble storage proteins of the Triticeae tribe of Gramineae family, are known as gliadin, secalin and hordein in wheat, rye and barley respectively. Prolamins were extracted from fifteen cultivars using DuPont protocol to study their physiochemical, morphological and structural characteristics. SDS-PAGE of prolamins showed well resolved low molecular weight proteins with significant amount of albumin and globulin as cross-contaminant. The β-sheet (32.72-37.41%) and β-turn (30.36-37.91%) were found higher in gliadins, while α-helix (20.32-28.95%) and random coil (9.05-10.28%) in hordeins. The high colloidal stability as depicted by zeta-potential was observed in gliadins (23.5-27.0 mV) followed secalins (11.2-16.6 mV) and hordeins (4.1-7.8 mV). Surface morphology by SEM illustrated the globular particle arrangement in gliadins, sheet like arrangement in secalins and stacked flaky particle arrangement in hordeins fraction. TEM studies showed that secalin and hordein fractions were globular in shape while gliadins in addition to globular structure also possessed rod-shaped particle arrangement. XRD pattern of prolamin fractions showed the ordered crystalline domain at 2θ values of 44.1°, 37.8° and 10.4°. The extracted prolamins fractions showed amorphous as well as crystalline structures as revealed by XRD and TEM analysis. Space saving hexagonal molecular symmetry was also observed in TEM molecular arrangement of prolamins which has profound application in development of plant-based polymers and fibres.
醇溶蛋白是禾本科小麦族的醇溶性贮藏蛋白，在小麦、黑麦和大麦中分别称为麦醇溶蛋白、黑麦碱和大麦醇溶蛋白。采用杜邦协议从15个品种中提取醇溶蛋白，以研究其物理化学、形态和结构特征。醇溶蛋白的SDS-PAGE显示低分子量蛋白分离良好，但有大量白蛋白和球蛋白作为交叉污染物。麦醇溶蛋白中β-折叠（32.72-37.41%）和β-转角（30.36-37.91%）含量较高，而大麦醇溶蛋白中α-螺旋（20.32-28.95%）和无规卷曲（9.05-10.28%）含量较高。由zeta电位表示的高胶体稳定性在麦醇溶蛋白中观察到（23.5-27.0 mV），其次是黑麦碱（11.2-16.6 mV）和大麦醇溶蛋白（4.1-7.8 mV）。扫描电子显微镜观察的表面形态表明，麦醇溶蛋白中有球状颗粒排列，黑麦碱中有片状排列，大麦醇溶蛋白组分中有堆叠的片状颗粒排列。透射电子显微镜研究表明，黑麦碱和大麦醇溶蛋白组分呈球状，而麦醇溶蛋白除球状结构外还具有棒状颗粒排列。醇溶蛋白组分的X射线衍射图谱在2θ值为44.1°、37.8°和10.4°处显示出有序的结晶域。X射线衍射和透射电子显微镜分析表明，提取的醇溶蛋白组分具有无定形和结晶结构。在醇溶蛋白的透射电子显微镜分子排列中还观察到节省空间的六边形分子对称性，这在植物基聚合物和纤维的开发中具有深远的应用。
