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Purification and characterization of an analgesic peptide from Buthus martensii Karsch.

The scorpion Buthus martensii Karsch (BmK) has been one of the indispensable materials in Chinese traditional medicine for thousands of years. In this work, an analgesic peptide was purified through four continuous chromatographic steps. The mouse twisting test was used to identify the target peptides in every separation step. The molecular weight, isoelectric point, and N-terminal residues of the purified peptide were determined. Based on the N-terminal sequence, the cDNA was also cloned by rapid amplification of cDNA ends from the cDNA pool of scorpion glands. This peptide was identical to BmK AS, an agonist of rabbit skeletal muscle ryanodine receptors. Preliminary pharmacodynamics revealed the following: the dose-effect curve plotted by the mouse twisting test showed an ED(50) of 1.42 mg/kg; and the time-effect curves plotted by a hot plate procedure showed a similar effect to the painkiller morphine. We report a purification procedure that yields substantial amounts of natural BmK AS having high activity. BmK AS has the potential to become a new analgesic medicine.