High-level expression and purification of an analgesic peptide from Buthus martensii Karch.

BmK AngM1, a scorpion peptide isolated from Buthus martensii Karch was reported to exhibit potential analgesic effect. But the relative low content of this toxin in crude venom limits its further characterization. In this study, we constructed an expression vector and transformed into E.coli. The BmK AngM1 was expressed as a fusion protein in the soluble fraction and was purified by Nickel affinity chromatography. Subsequently, the purified fusion protein was cleaved by enterokinase and was further purified by reverse-phase HPLC. We purified 25 mg recombinant BmK AngM1 (rBmK AngM1) from 1 L bacterial culture. The molecular weight of rBmK AngM1 determined by ESI-MS was 7240.4 Da which was the expected size for correctly processed. Analgesic bioassay studies of rBmK AngM1 exhibited its potential analgesic effect comparable to that of the natural BmK AngM1 peptide.