1s8k

Solution Structure of BmKK4, A Novel Potassium Channel Blocker from Scorpion Buthus martensii Karsch, 25 structures

spinqualitylabelsall models 1s8k, 25 NMR models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1s8k is a 1 chain structure with sequence from Mesobuthus martensii. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: NH2, PCA Related: 1du9, 1pnh, 1acw, 1scy Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [KA171_MESMA] Blocker of potassium channels, which inhibits both the delayed rectifier and fast transient potassium current. The inhibition is reversible and voltage-independent. It causes a depolarizing shift of the steady-state activation curve of the currents, without changing their steady-state inactivation behavior. Publication Abstract from PubMed BmKK4 is a 30 amino acid peptide purified from the venom of the Chinese scorpion Buthus martensi Karsch. It has been classified as the first member of scorpion toxin subfamily alpha-KTx 17. The 3D structure of BmKK4 in solution has been determined by 2D NMR spectroscopy. This toxin adopts a common alpha/beta-motif, but shows a distinctive local conformation. The most novel feature is that the regular arrangements of the side chains of the residues involved in the beta-sheet of BmKK4 are distorted by a classic beta-bulge structure, which involves two residues (Asp18 and Arg19) in the first strand opposite a single residue (Tyr26) in the second strand. The bulge produces two main changes in the structure of the antiparallel beta-sheet: (1) It disrupts the normal alteration of the side chain direction; the side chain of Asp18 turns over to form a salt bridge with that of Arg19. (2) It accentuates the twist of the sheet, and alters the direction of the antiparallel beta-sheet. The unusual structural feature of the toxin is attributed to the shorter peptide segment (Leu15-Arg19) between the third and fourth Cys residues and two unique residues (Asp18 and Arg19) at the position preceding the fourth Cys. In addition, the lower affinity of the peptide for the Kv channel is correlated to the structural features: residue Arg19 instead of a Lys residue at the critical position for binding and the salt bridge formed between residues Arg19 and Asp18. Solution structure of BmKK4, the first member of subfamily alpha-KTx 17 of scorpion toxins.,Zhang N, Chen X, Li M, Cao C, Wang Y, Wu G, Hu G, Wu H Biochemistry. 2004 Oct 5;43(39):12469-76. PMID:15449936 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Potassium channel toxin 3D structures

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