Purification And Isolation Of Chinese Buthus Martensi Karsch Polypeptides And Its Effects On Sodium And Potassium Channels

Part one: The purification, isolation and identification of Buthus martensi Karsch(BmK) neurotoxinsBmK2-2-5-5, BmK2-2-5-5-l and BmK2-2-5-6, BmK2-2-5-6-l were purified and isolated from scorpion crude venom by classical chromatographic method, and we studied the primary characterization and identification of these peptides. It showed: (1) Both of BmK2-2-5-5-l and BmK2-2-5-6-l revealed end absorption by UV scan, which the absorbency is the highest at 206nm or so. The MW of the twocomponents are 7214.36 Da and 7036.85 Da. (2) Acid amino analysis was used to determinate the relative ratio of the acid amino residues of BmK2-2-5-5-l: Asp: Thr: Ser: Glu: Gly: Ala: Val: Met: Iie: Leu: Tyr: Phe: Lys: His: Arg≈4: 1: 8: 4: 10: 4: 4: 2: 2: 2: 2: 2: 2: 1: 2. (3) The sequence of BmK2-2-5-6 is GRDAY IADSE NCTYT by Edman degradation; and those three peptides did not detect any signals because of N-terminal blocked.Part two: Effects of BmK2-2-5-5 and BmK2-2-5-5-l on Na~+currents and K~+currents in rat dorsal root ganglion neuronsThe effects of BmK2-2-5-5 and BmK2-2-5-5-l, polypeptides purified from Buthus martensi Karsch (BmK) venom, on Na~+ currents and K~+ currents in rat DRG neurons were investigated in this part using Whole-cell patch clamping technique. The results indicated as follows: (1) BmK2-2-5-5 does not exert significant effects on the sodium channel and the peak Na~+ currents at 50μg/ml; but at the concentration of 75μg/ml BmK2-2-5-5 showed significant increasing effects on the potassium channel in rat DRG neurons, while the outward potassium currents, the delayed rectifier potassium currents and the fast inactivating potassium currents were increased to 40.32 ± 10.13%(n=3), 33.22 ± 10.59%(n=3)...