Processing Technology Research of Fermentation and Purification of SUMO Protease UlP1 / 中国生物工程杂志

Nowadays,small peptides are always expressed in the form of fusion protein.The expression product contains many superfluous amino acids which can affect the biological functions of small peptides even expressed by GST fusion protein expression system.SUMO protease can cut SUMO fusion protein expressed by fusion expression system without any amino acid residues left on target protein thus become a hot topic in this field.Recombinant His-UlP1/pET3c/BL21(DE3)engineering strain was constructed by genetic engineering technology and the expression conditions were optimized in shake flaks.The process of high density fermentation was explored and different purification conditions were detected by chromatography.The results showed that SUMO protease could be expressed well after inducing the engineering strain by IPTG of 1.0mmol/L at 30℃ for 6 hours.The expression level of the strain in fermentation pots could reach 24.3% analyzed by SDS-PAGE.The purity of SUMO protease was more than 98% after further purification by cation exchange chromatography.The yield was 355mg SUMO protease per liter fermentation liquid.Western blot analysis demonstrated that there were immune reactions between IlP1 and 6?His antibodies,so it has established a good foundation for large-scale industralazation in the future.

Profiling Membrane Proteome of Macrophages by One-dimensional PAGE and Liquid Chromatography-Tandem Mass Spectrometry / 中国生物工程杂志

Macrophages are involved in many important biological processes and membrane proteins are the key effector molecules for their functions. However, membrane proteins are difficult to analyze by 2-DE based method because of their intrinsic tendency to self-aggregate during the first dimension separation (IEF). To circumvent the obstacle hampering membrane protein analysis, we combined one-dimensional SDS-PAGE with capillary liquid chromatography-tandem mass spectrometry (LC-MS/MS). Using this technique, we identified 458 GO annotated membrane proteins with extremely high confidence, including most known markers of peritoneal macrophages (e.g., CD11b, F4/80, CD14, CD18, CD86, CD44, CD16 and Toll-like receptor). Thirteen other CD antigens and 18 Ras-related small GTPase were also identified. In addition to those known macrophage membrane proteins, a significant number of novel proteins have also been identified. This research provides a valuable data set of macrophage membrane proteins, thus allowing for more comprehensive study of membrane proteins and a better understanding of the function mechanisms of macrophages in many biological processes.

The Study of Expression HBcAg and HBsAg preS1 Epitope Peptide Fusion Protein / 中国生物工程杂志

To construct, express and purify fusion protein containing HBcAg and HBsAg preS1 epitope peptide for the purpose of investigating a novel HBV vaccine with both prophylactic and therapeutic functions. Using DNA recombinant technology, prokaryotic expression plasmid pBTcs1 expressing HBcAg and HBsAg pre-S1 epitope peptide fusion protein was constructed. After expressed in E.coli. HB101, the production BTcs1 was purified by sucrose density gradient ultracentrifugation and identified by SDS-PAGE, SEC, Western-blot and electron microscope. The results indicated that expression plasmid pBTcs1 was constructed successfully, and 20~25 mg purified BTcs1 fusion protein was obtained from 1L LB culture. Result of DOT-BLOT indicated that the distribution of BTcs1 was mainly in 30~50% sucrose, the purity of BTcs1 was greater than 95% by SDS-PAGE and SEC analysis. BTcs1 could probe with specific antibodies at 28 kDa by Western-blot, BTcs1 could also self assemble VLP by electron microscope analysis, its diameter was 30~34 nm approximately. The present study lay a foundation for further research functions and applications of BTcs1.