莲子蛋白组分二级结构的研究

对莲子蛋白质进行了Osborne蛋白质分类。采用傅里叶变换红外光谱(FTIR)对清蛋白、球蛋白、醇溶蛋白和谷蛋白进行二级结构分析。应用去卷积和曲线拟合方法对四种蛋白组分的酰胺Ⅰ和Ⅲ带进行分析,清蛋白和球蛋白之间以及醇溶蛋白和谷蛋白之间各相应子峰峰位和二级结构峰面积百分比差异较小,但前两者各相应子峰峰位与后两者略有差异;而前两者各相应二级结构峰面积百分比与后两者有较大差异,特别是前两者的各相应有序结构(α-螺旋+β-折叠)峰面积的百分比明显大于后两者。用0.1 mol.L-1NaCl溶液提取的球蛋白和清蛋白有序结构含量均在55%左右,而醇或碱提的醇溶蛋白和谷蛋白的有序结构含量仅为40%左右,盐提的蛋白质二级结构有序性和稳定性更高。

Second structure of the protein factions from lotus seeds

Following the sequential Osborne extraction procedure, the proteins of lotus seeds were classified. The secondary structures of albumin, globulin, prolamine and glutelin fractions were determined by Fourier transform infrared spectroscopy (FTIR). The FTIR images of amide I and III bands from the four protein fractions were analyzed using Fourier deconvolution and curve-fitting technique. The results showed that there were minor differences in every corresponding peak position and peak area percent of secondary structure between albumin and globulin as well as between prolamin and glutelin. But there were differences in every corresponding peak position between albumin (or globulin) and prolamin (or glutelin). Especially the area percents of the corresponding nonrandom structures (alpha-helix and beta-sheet) of albumin and globulin were significantly larger than those of prolamin and glutelin. The contents of nonrandom structures of albumin and globulin extracted with 0.1 mol x L(-1) NaCl solution were about 55% and those of prolamine and glutelin fractions were only at round 40%, indicating that the secondary structures of the salt-extraction protein were ordered and stable.