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Cloning, overexpression, folding and purification of a biosynthetically derived three disulfide scorpion toxin (BTK-2) from Mesobuthus tamulus

Kumar, G Senthil and Sarma, Siddhartha P (2010) Cloning, overexpression, folding and purification of a biosynthetically derived three disulfide scorpion toxin (BTK-2) from Mesobuthus tamulus. In: Protein Expression and Purification, 70 (2). pp. 137-142.

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BTK-2, a 32 residue scorpion toxin initially identified in the venom of red Indian scorpion Mesobuthus tamulus was cloned, overexpressed and purified using Cytochrome 155 fusion protein system developed in our laboratory. The synthetic gene coding for the peptide was designed taking into account optimal codon usage by Escherichia coli. High expression levels of the fusion protein enabled facile purification of this peptide. The presence of disulfide bonded isomers, occurring as distinctly populated states even in the fusion protein, were separated by gel filtration chromatography. The target peptide was liberated from the host protein by Tev protease cleavage and subsequent purification was achieved using RP-HPLC methods. Reverse phase HPLC clearly showed the presence of at least two isomeric forms of the peptide that were significantly populated. The oxidative folding of BTK-2 was achieved under ambient conditions during the course of purification. Structural characterization of the two forms, by solution homonuclear and heteronuclear NMR methods, has shown that these two forms exhibit significantly different structural properties, and represent the natively folded and a "misfolded" form of the peptide. The formation of properly folded BTK-2 as a major fraction without the use of in vitro oxidative refolding methods clearly indicate the versatility of the Cytochrome b(5) fusion protein system for the efficient production of peptides for high resolution NMR studies.

Item Type: Journal Article
Publication: Protein Expression and Purification
Publisher: Elsevier Science.
Additional Information: Copyright of this article belongs to Elsevier Science.
Keywords: Animal toxins; Biosynthetic production; Disulfide rich peptides; Heteronuclear NMR; Fusion proteins; Isotopic labeling
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 24 Mar 2010 10:31
Last Modified: 19 Sep 2010 05:57
URI: http://eprints.iisc.ac.in/id/eprint/26380

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