Annexin A5 ; biosynthesis ; isolation & purification ; Escherichia coli ; metabolism ; Genetic Vectors ; Humans ; Recombinant Proteins ; biosynthesis ; isolation & purification

Recombinant adeno-associated virus (rAAV)-based vectors that can stably express therapeutic genes in vivo without detectable side-effect have shown great promise for human gene therapy. A major challenge for translation of promising research to clinical development is how to establish clinically compatible purification methods in separating rAAV from potentially pathogenic impurities, especially rAAV vector-related impurities, a class of impurities corresponding to AAV particles that closely resemble bona fide vectors and are difficult to remove. In this review we summarize the assembly process of rAAV vector-related impurities and their characteristics differed with rAAV vectors, and evaluate several current technologies to prevent their formation or separate them from rAAV stocks.
Capsid Proteins ; isolation & purification ; Dependovirus ; genetics ; isolation & purification ; physiology ; Genetic Therapy ; methods ; Genetic Vectors ; genetics ; isolation & purification ; Recombination, Genetic ; Virion ; isolation & purification ; Virus Assembly ; genetics ; Virus Replication ; genetics

Plasmid DNA (pDNA) is used as an important vector for gene therapy, and its wide application is restricted by the purity and yield. To obtain high-purity pDNA, a chromatographic method based on anion-exchange supermacroporous cryogel was explored. The anion-exchange cryogel was prepared by grafting diethylaminoethyl-dextran to the epoxide groups of polyacrylamide-based matrix and pUC19 plasmid was used as a target to test the method. The plasmid was transferred into Escherichia coli DH5alpha, cultivated, harvested and lysed. The obtained culture was centrifuged and the supernatant was used as the plasmid feedstock, which was loaded into the anion-exchange cryogel bed for chromatographic separation. By optimizing the pH of running buffer and the elution conditions, high-purity pDNA was obtained by elution with 0.5 mol/L sodium chloride solution at pH 6.6. Compared to the traditional methods for purification of pDNA, animal source enzymes and toxic reagents were not involved in the present separation process, ensuring the safety of both the purification operations and the obtained pDNA.
Anions ; Chromatography, Ion Exchange ; methods ; Cryogels ; chemical synthesis ; DNA ; isolation & purification ; Genetic Vectors ; isolation & purification ; Plasmids ; isolation & purification ; Porosity

The structure gene pelA from Thermotoga maritima MSB8 encoding pectate lyase was amplified and ligated into pHsh, resulting pHsh-pelA. Through structural optimization on pHsh-pelA, the ultimate plasmid, pHsh-pelC, which possessed the most appropriate structure and free energy of mRNA, was obtained. Pectate lyase C (PelC) was obtained after expressing pHsh-pelC in Escherichia coli JM109. The optimum activity of PelC was determined at pH 8.5 at 90 degrees C, with a half-life for almost 2 h at 95 degrees C. PelC was stable at the pH range of 8.2-9.8, and was dependent on Ca2+ for activity and stability. The enzyme kept stable for a long time and possessed a high level of activity at 60 degrees C. The kinetic assay using polygalacturonic acid (PGA) as substrate gave K(m) and V(max) of 0.11 mmol/L and 327 U per mg of protein. SDS-PAGE analysis showed that the molecular mass of the expressed recombinant PelC was about 43 kD, which was exactly the size predicted. The expression vector system of the heat shock plasmid pHsh owned such advantages as high expression level and cheap induction. Moreover, the superior stability of the recombinant enzyme laid the base for large-scale fermentation application.
Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Hot Temperature ; Polysaccharide-Lyases ; biosynthesis ; genetics ; isolation & purification ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification ; Recombination, Genetic ; Thermotoga maritima ; enzymology

Elastin-like polypeptides (ELPs) are temperature sensitive biopolymers composed of a Val-Pro-Gly-Xaa-Gly pentapeptide repeat that derived from a structural motif found in mammalian elastin. It was a promising tag for recombinant protein purification. Here, we de novo designed a novel ELPs gene and cloned it into the modified expression vector pET-22b(+). Then, we transformed the recombinant expression vector pET-22b-ELPs into Escherichia coli BL21(DE3). Upon induction by Isopropyl beta-D-Thiogalactoside (IPTG), ELPs was expressed and purified by a non-chromatographic purification method named inverse temperature cycling. The influences of salts types and concentrations on ELPs were also determined. The results showed that the transition temperature of the [KV8F-20] decreased to 19 degrees C by 0.4 mmol/L Na2CO3. Due to its small molecular weight and sensitivity to salt, the ELPs might be a useful purification tag, which can provide a reliable and simple non-chromatographic method for purification of the recombinant protein by inverse transition cycling.
Chromatography ; Elastin ; biosynthesis ; genetics ; isolation & purification ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Peptides ; genetics ; isolation & purification ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; Sodium Chloride ; pharmacology

A DNA fragment encoding extracellular domain of mouse epidermal growth factor receptor (EGFR) was obtained by PCR from a previous recombinant plasmid. The DNA fragment was then ligated into prokaryotic expression vector, and expressed in Escherichia Coli. The recombinant protein was purified under denature conditions by affinity chromatography, and refolded with gradient dialysis. The recombinant protein could produce antibodies to recognize extracellular domain and full-length of mouse EGFR, and form homodimer in the presence of EGF detected by western blot analysis. These findings provide evidence that the renatured recombinant extracellular domain of mouse epidermal growth factor receptor is immunogenetic and may be important for further application of this protein in functional and immunological research.
Animals ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Mice ; Plasmids ; Receptor, Epidermal Growth Factor ; biosynthesis ; chemistry ; genetics ; isolation & purification ; Transfection

A DNA fragment encoding recombinant human interleukin 11 (hrIL-11) was obtained by PCR from previously constructed pET24a-hrIL-11 plasmid. Then pET21a-hrIL-11 expression vector was constructed routinely and transformed into BL-21(DE3). By the induction of Isopropyl-1-thio-beta-D-galactoside (IPTG), hrIL-11 protein was highly expressed at about 20% of the total bacterial proteins and was identified by Western blot. After purification with Ni-NTA affinity chromatography and refolding with renaturation buffer, the purity of the target hrIL-11 protein reached 95% and its biology activity was 1 x 10(6) IU/mg, determined by stimulating the proliferation of T1165, which facilitates further researches into effects of IL-11 on platelet proliferation and other function.
Escherichia coli ; metabolism ; Genetic Vectors ; genetics ; Humans ; Interleukin-11 ; genetics ; metabolism ; Recombinant Proteins ; genetics ; isolation & purification ; metabolism

OBJECTIVETo prepare the trimeric subunits of recombinant human mannan-binding lectin (MBL) with biological activities.

METHODSA prokaryotic expression vector containing human MBL N-terminal deletant (rhMBLδN) gene we previously constructed was transformed into E. coli for efficient expression of rhMBLδN fusion protein. Based on the principle that the collagen polypeptides tend to self-assembly into the tertiary structure of proteins by forming a triple helix due to the characteristic properties of the collagen proteins, rhMBLδN fusion protein was limitedly hydrolyzed with thrombin. The obtained rhMBLδN polypeptide was repeatedly dialyzed in 50 mmol/L PBS (pH7.2) and ddH(2)O, and the final product was analyzed for its bioactivities using a ligand-binding assay and a C4d deposition assay.

RESULTSrhMBLδN polypeptide with a relative molecular mass of about 20 000 was obtained by limited proteolysis of rhMBLδN fusion protein with thrombin. Repeated dialyses of rhMBLδN polypeptides in 50 mmol/L PBS and ddH(2)O resulted in the isolation of the trimeric subunit trhMBLδN (with a relative molecular mass of about 50 000), which contained a collagen-like helix. The trhMBLδN protein had a higher ligand-binding activity than rhMBLδN polypeptide, and acquired the activity to initiate the lectin pathway of complement activation, but the activities were lower than those of natural MBL.

CONCLUSIONWe have successfully obtained the bioactive trimeric subunit of rhMBL, trhMBLδN, and this structural subunit is also the functional subunit of the MBL molecule.

Complement Activation ; Escherichia coli ; metabolism ; Genetic Vectors ; Humans ; Mannose-Binding Lectin ; biosynthesis ; genetics ; isolation & purification ; Recombinant Proteins ; biosynthesis

Cytochrome C plays important roles in electron transferring, oxidative stress and apoptosis. In this study, soluble cytochrome C was accumulated in cytoplasm of E. coli by utilizing the co-expression of human cytochrome c and yeast heme lyase from a single plasmid. After ultrasonic disruption of the bacteria, a lot of contaminated proteins were discarded by addition of 350 g/L ammonium sulfate into the supernatant. Then the recombinant human cytochrome C was purified to 80% homogeneity after two times cation exchange chromatography on SP-Sepharose Fast Flow. Yields of cytochrome C greater than 10 mg per liter culture were attained. This efficient system for producing human cytochrome C is helpful for us to understand the roles of this protein in biological processes and therapy of human diseases relevant to apoptosis and oxidative stress.
Cytochromes c ; biosynthesis ; genetics ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Humans ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification

OBJECTIVETo establish a method for the expression of glycogen synthase kinase 3β with high purity and biological activity.

METHODSE.coli expression system and baculovirus-insect cell expression system were used to produce the kinase, followed by purification using His-tag and GST-tag and determination of its purity and activity by SDS-PAGE and kinase reaction, respectively.

RESULTSGlycogen synthase kinase 3β produced from E.coli represented 54% of the total bacterial protein, as compared with 96% of the total protein from the insect cell system .Glycogen synthase kinase 3β produced from insect cell exhibited an one-fold higher biological activity than the protein obtained from E.coli.

CONCLUSIONSCompared with the protein from E.coli system, glycogen synthase kinase 3β from the insect cell expression system is endowed with a higher purity and bioactivity.

Animals ; Baculoviridae ; metabolism ; Escherichia coli ; metabolism ; Genetic Vectors ; Glycogen Synthase Kinase 3 ; biosynthesis ; isolation & purification ; Insecta ; cytology