Three-dimensional structure of a protein from scorpion venom: a new structural class of neurotoxins.

摘要: Abstract The three-dimensional crystal structure of variant-3 toxin from the scorpion Centruroides sculpturatus Ewing has been determined at 3 A resolution. Phases were obtained by use K2PtCl4 and K2IrCl6 derivatives. The most prominent secondary structural features are two a half turns alpha-helix three-strand stretch antiparallel beta-sheet, which runs parallel to alpha-helix. helix is connected middle strand beta-sheet disulfide bridges; third bridge located nearby. Several loops extend out this dense core structure. largest loop joined COOH terminus molecule fourth bridge. overall shape resembles right-hand fist: along knuckles fist; lies second joints fingers; thumb defined short that composed residues 16-21 41-46; wrist corresponds COOH-terminal 52-65 5-14; joint little finger near NH2 molecule. alpha-carbon backbone displays large flat surface fingers heel hand in fist model. conserved neurotoxins clustered on surface, may play role interactions toxins with sodium channels excitable membranes.