Effect study of different methods to extract protein from sweet potato tuberous roots

In order to establish a two-dimensional electrophoresis system for the proteomics study of sweet potato tuberous roots, this study compared four protein extraction methods(homogenate method, acetone precipitation method, TCA- acetone precipitation method and phenol method). Then we evaluated these four protein preparation methods through different parameters, such as protein yield, SDS-PAGE and 2-DE techniques. In this experiment, 1.6 mg, 2.4 mg, 1.2 mg and1.9 mg soluble protein was yielded from 0.5 g fresh potato tuber using these 4 protein extraction methods, respectively. The SDSPAGE results showed that the homogenate method and acetone precipitation method generated only few protein bands with high storage protein content(about M r 20 × 103). By contrast, the TCA- acetone precipitation method and phenol method could separate more protein bands, with much lower band of storage protein. On 2-DE gels, the homogenization method could hardly complete the IEF, with only a few protein spots appearing in its alkaline end. The results of acetone method and TCA-acetone precipitation method were obviously better than homogenization method, but the number of protein was still less than phenol method. The number of protein spot obtained by phenol method was the most, and these protein spots were evenly distributed in the 2-DE gel. In summary, the phenol extraction method is suitable for sample preparation of sweet potato tuber for twodimensional electrophoresis.