莲子磨皮粉中蛋白质的提取、组成及性质

Extraction, Composition and Molecular Properties of Proteins from Lotus Seed Peel Powder

采用碱溶酸沉法提取莲子磨皮粉中的蛋白质,并以莲子中提取的蛋白质作对照,采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳、体积排阻色谱法测定了两种蛋白质的组成差异,采用差示扫描量热仪及傅里叶红外光谱对两种蛋白质的部分性质和结构进行了表征。结果显示:碱溶酸沉法提取莲子磨皮粉和莲子蛋白质的提取率分别为72.24%和78.93%;凝胶电泳图谱显示,莲子磨皮粉蛋白质亚基分子质量分布在15~70 k D,而莲子蛋白质亚基分子质量分布在10~45 k D;体积排阻色谱图谱也显示莲子磨皮粉蛋白质中包含有更多的不同分子质量的蛋白质组分;差示扫描量热仪分析显示,莲子磨皮粉蛋白质的变性峰值温度为118.28℃,莲子蛋白质为108.05℃,且莲子磨皮粉蛋白质变性焓值更高,因而蛋白质空间结构有序性较高;傅里叶红外光谱分析也揭示莲子磨皮粉蛋白质相比于莲子蛋白质构象更为有序。

In the present study, lotus seed peelpowder protein(LSPP) and lotus seed protein(LSP) were extracted by alkali solubilization and isoelectric precipitation. Sodium dodecyl sulfonate-polyacrylamide gel electrophoresis(SDS-PAGE) and size-exclusion high performance liquid chromatography(SEC-HPLC) were used to examine the differences in the composition of the extracted proteins. Differential scanning calorimetry(DSC) and Fourier transform infrared spectrometer(FT-IR) were used to characterize some properties and structures of LSPP and LSP. The results showed that the extraction rates of proteins from lotus seed peel powder and lotus seed were 72.24% and 78.93%, respectively. SDS-PAGE analysis revealed that the molecular weights of LSPP subunits were distributed in the range from 15 to 70 k D, while those of LSP in the range from 10 to 45 k D. SEC-HPLC also revealed that LSPP was composed of a larger number of molecular fractions than LSP. DSC analysis showed that denaturation peak temperatures of LSPP and LSP were 118.28 ℃ and 108.05 ℃, respectively, and the former had a higher enthalpy of denaturation. These results combined with FT-IR analysis results showed that the conformation of LSPP was more regular.