title: Purification and pharmacological characterization of BmKK2 (alpha-KTx 14.2), a novel potassium channel-blocking peptide, from the venom of Asian scorpion Buthus martensi Karsch.
abstract: BmKK2 (alpha-KTx 14.2) is one of the novel short-chain peptides found in molecular cloning of a venom gland cDNA library from Asian scorpion Buthus martensi Karsch. Based upon its amino acid sequence, the peptide was proposed to adopt a classical alpha/beta-scaffold for alpha-KTxs. In the present study, we purified BmKK2 from the venom of B. martensi Karsch, and investigated its action on voltage-dependent K+ currents in dissociated hippocampal neurons from neonatal rats. BmKK2 (10-100 microM) selectively inhibited the delayed rectifier K+ current, but did not affect the fast transient K+ current. The inhibition of BmKK2 on the delayed rectifier K+ current was reversible and voltage-independent. The peptide did not affect the steady-state activation of the current, but caused a depolarizing shift (about 9 mV) of its steady-state inactivation curve. The results demonstrate that BmKK2 is a novel K+ channel-blocking scorpion peptide.
authors.affiliation: State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 555 Zu-Chong-Zhi Road, Shanghai 201203, China.
authors.forename: Ming-Hua
authors.initials: MH
authors.lastname: Li
authors.forename: Nai-Xia
authors.initials: NX
authors.lastname: Zhang
authors.forename: Xue-Qin
authors.initials: XQ
authors.lastname: Chen
authors.forename: Gong
authors.initials: G
authors.lastname: Wu
authors.forename: Houming
authors.initials: H
authors.lastname: Wu
authors.forename: Guo-Yuan
authors.initials: GY
authors.lastname: Hu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D015723:Gene Library; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D012604:Scorpion Venoms / Q000302:isolation & purification / Q000494:pharmacology*; D012605:Scorpions / Q000737:chemistry*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013997:Time Factors
chemical_list: C445369:KK toxin, Buthus martensi; D026902:Potassium Channel Blockers; D012604:Scorpion Venoms