Anti-cisplatin-induced Renal-injury Effect of Human Manganese Superoxide Dismutase with Leader Peptide / 肿瘤防治研究

Objective To investigate the effect of the fusion of leader peptide on the structure of human manganese superoxide dismutase (SOD2) and anti-cisplatin (DDP)-induced renal injury. Methods The effect of mitochondrion targeting sequence (MTS) on the structure and activity of SOD2 was analyzed by structure prediction and superoxide dismutase (SOD) specific-activity determination. The DDP injury model of Kunming (KM) mice was established, and amifostine (AMFT) was set as a positive control. Indicators such as kidney index, renal function, kidney antioxidant capacity, and appearance and pathology changes of mice kidney were used to evaluate the effect of MTS-SOD2 against DDP-induced kidney injury. Results The MTS leader peptide seemed to change the secondary and tertiary structures of SOD2 to some extent, but it also increased the specific activity of the MTS-SOD2 protein. Pre-administration of a medium dose of MTS-SOD2 (0.84 mg/kg) before the use of DDP significantly reduced the level of renal malondialdehyde and increased the SOD activity and total antioxidant capacity (T-AOC) in the kidney, thereby reducing the renal pathological damage and consequently maintaining renal function. The overall protective effect of MTS-SOD2 was comparable to or even better than that of 200 mg/kg AMFT. Conclusion The MTS leader peptide enhances the activity of SOD2 and confers it with an excellent anti-DDP-induced renal-injury effect because of its transmembrane function.

Purification and characterization of two PR-10 protein isoforms from the crude drug of Angelica sinensis / 生物工程学报

Two proteins of similar molecular weight (named as ASPR-C-1 and ASPR-C-2) from the crude drug of Angelica sinensis were purified and characterized by 80% ammonium sulfate precipitation, Sephadex G-50 gel filtration chromatography, and DEAE-Sepharose anion exchange chromatography. The molecular weight of ASPR-C-1 and ASPR-C-2 on SDS-PAGE was 17.33 kDa and 17.18 kDa, respectively. They were mainly monomeric in solution, but partially formed dimers and they were glycoproteins with glycosyl content of 2.6% and 8.2%, respectively. Both ASPR-C-1 and ASPR-C-2 were identified to be members of pathogenesis-related 10 family of proteins by matrix-assisted laser desorption ionization time-of-flight mass spectrometry and have ribonuclease activities with the specific activity of 73.60 U/mg and 146.76 U/mg, respectively. The optimum pH of the two isoforms was similar, at about 5.6, while their optimum temperatures were different. The optimum temperature of ASPR-C-1 was 50 ℃, and that of ASPR-C-2 was 60 ℃. Both isoforms presented highest thermal stability at 60 ℃. However, ASPR-C-2 was more thermotolerant than ASPR-C-1. The latter was rapidly inactivated and retained only about 20% residual activity while the former still maintained about 80% of its original activity at a higher treatment temperature (80 to 100 ℃). In addition, Fe²⁺ had an activating effect on the ribonuclease activities of two isoforms while Ca²⁺, Mg²⁺, Zn²⁺, Mn²⁺, Ag⁺, Cu²⁺, EDTA (Elhylene diamine tetraacetic acid), dithiothreitol and sodium dodecylsulphate showed different degrees of inhibition of the enzyme activities. Our findings provide a foundation for further research on the biological function of PR-10 protein from Angelica sinensis.

Expression, purification, stability and transduction efficiency of full-length SOD2 recombinant proteins / 生物工程学报

Superoxide dismutase (SOD) family is necessary to protect cells from the toxicity of reactive oxygen species produced during normal metabolism. Among SODs, manganese-containing superoxide dismutase (Mn-SOD, SOD2) is the most important one. The DNA fragment containing the full nucleotide of full-length human SOD2 was synthesized and inserted into the prokaryotic expression vector pGEX-4T-1 with tag GST. DNA construct was then transformed into Escherichia coli BL21 (DE3) and expression was induced with IPTG at 25 ℃. The recombinant fusion protein GST-SOD2 (46 kDa) was purified from the bacterial lysate by GST resin column affinity chromatography. GST tag was cleaved with thrombin, and a crude SOD2 recombinant protein (25 kDa) was obtained and further purified by heparin affinity chromatography. Activities of the two SOD2 proteins were 1 788 and 2 000 U/mg, respectively. Both SOD2 proteins were stable under physiological condition and cell-penetrating (P<0.05). Our findings open the possibility to study the structure and effects of two full-length recombinant SOD2 proteins.

Expression, purification, stability and transduction efficiency of GST-SOD1-R9 fusion protein / 生物工程学报

The fusion of cell permeable peptide TAT and bifunctional antioxidant enzymes, GST (Glutathione sulfur transferase)-TAT-SOD1 (Cu, Zn superoxide dismutase), is an intracellular superoxide scavenger. Compared with SOD1-TAT, GST-TAT-SOD1 has better protective effect on oxidative damage but less transduction efficiency. A novel cell permeable bifunctional antioxidant enzymes with the fusion of GST, SOD1 and polyarginine R9 was constructed for higher transduction efficiency. The full nucleotide sequence of SOD1-R9 was synthesized and inserted into the prokaryotic expression vector pGEX-4T-1 with the GST tag. After the successful construction of the prokaryotic expression vectors of GST-SOD1-R9, the recombinant vector was then transformed into Escherichia coli BL21 (DE3) and the GST-SOD1-R9 fusion protein was produced with the induction of IPTG. The soluble expression of GST-SOD1-R9 fusion protein was combining with the induction temperature and time. The best soluble expression was obtained with the induction temperature of 25 ℃ and the induction time of 11 h. The fusion protein was purified through the combination of 80% ammonium sulfate precipitation and affinity chromatography using glutathione agarose, and verified by SDS-PAGE and special enzymatic activity. The thermal and pH stability of GST-SOD1-R9 fusion protein were analyzed and the SOD and GST activity of fusion protein were proved to be well maintained under physiological conditions. Finally, the transduction efficiency of GST-SOD1-R9 fusion protein was proved to be better than GST-TAT-SOD1 fusion protein (P<0.05). These works establish a foundation for further study of the protective effect of GST-SOD1-R9 fusion protein against oxidative damage.

PTD mediated protein transduction technology and its application in medical field / 生物医学工程学杂志

The delivery of bioactive macromolecular substances into cells provides an efficient approach to changing cellular conditions, and is thus of enormously potential therapeutic significance. It has also been an extremely difficult approach due the the impediment and protective nature of cell membrance until the protein transduction domain's (PTD's) capability to ferry macromolecule across cell membrance was discovered. PTD's efficient transductive function has rendered an exciting promise to the clinical treatment of diseases, therapeutic proteins drug development, and basic medical and applied research. The technology has been successfully applied to deliver a variety of substances into cells or tissue organs, and its superior application values have been explicitly demonstrated.