Scalable production of recombinant three-finger proteins: from inclusion bodies to high quality molecular probes.

BACKGROUND: The three-finger proteins are a collection of disulfide bond rich proteins of great biomedical interests. Scalable recombinant expression and purification of bioactive three-finger proteins is quite difficult. RESULTS: We introduce a working pipeline for expression, purification and validation of disulfide-bond rich three-finger proteins using E. coli as the expression host. With this pipeline, we have successfully obtained highly purified and bioactive recombinant α-Βungarotoxin, k-Bungarotoxin, Hannalgesin, Mambalgin-1, α-Cobratoxin, MTα, Slurp1, Pate B etc. Milligrams to hundreds of milligrams of recombinant three finger proteins were obtained within weeks in the lab. The recombinant proteins showed specificity in binding assay and six of them were crystallized and structurally validated using X-ray diffraction protein crystallography. CONCLUSIONS: Our pipeline allows refolding and purifying recombinant three finger proteins under optimized conditions and can be scaled up for massive production of three finger proteins. As many three finger proteins have attractive therapeutic or research interests and due to the extremely high quality of the recombinant three finger proteins we obtained, our method provides a competitive alternative to either their native counterparts or chemically synthetic ones and should facilitate related research and applications.

Site-directed Mutagenesis and Enzymatic Activity Assay of Gln49-Phospholipase A_2 Mutant / 中国生物工程杂志

In order to confirm the role that the 49th amino acid residue plays in enzymatic inactivity of Glutamine 49 phospholipase A2(Gln49-PLA2),site-directed mutagenesis of its 49th amino acid gene codon was conducted using PCR.Aspartic acid 49 phospholipase A2(Asp49-PLA2-Q49D-PLA2),the mutant of Gln49-PLA2 was expressed in E.coli with pET32a+ vector.The fusion protein,expressed as inclusion body,after being denatured,was on-column refolded and purified by immobilized metal affinity chromatography(IMAC),and then cleaved by Factor Xa.The mature Q49D-PLA2 mutant was obtained by Hitrap SP cation exchange and Superdex 75 gel filtration chromatography,with the recovery rate of 1.3%,and the specific activity of the mature Q49D-PLA2 mutant was 72 U/mg.It has been demonstrated that the 49th glutamine amino acid residue is the main reason in enzymatic inactivity of Gln49-PLA2 and the results are helpful for denatured protein refolding,especially in rich disulfide bonds conditions.