1CHZ: A New Neurotoxin From Buthus Martensii Karsch

Citation:
Abstract
A new neurotoxin BmK M2, toxic to both mammals and insects, with the strongest toxicity in the BmK toxin series, has been purified from the Chinese scorpion Buthus martensii Karsch and crystallized with MPD at pH 7.5. The crystals are orthorhombic, belonging to space group P2(1)2(1)2(1), with unit-cell parameters a = 36.64, b = 36.95, c = 37.23 A. The structure was solved by molecular replacement and refined to R = 0.186 for all reflections to a resolution of 1.76 A. The whole sequence (64 residues) of BmK M2 was determined by crystallographic analysis based on high-resolution data and the homologous model of BmK M8. The refined BmK M2 structure shows a non-proline cis peptide bond between Pro9 and His10 which enables the C-terminal segment to adopt a conformation different to that of the weak toxin BmK M8. Recently, a mutation analysis had suggested that both the tenth residue and the C-terminus play key roles in receptor binding. Therefore, these features may be related to the binding selectivity of the group III alpha-like toxins. The charge changes of residues 8, 10, 18, 28, 55 and 59 from neutral or negative to positive or neutral, which leads to a positive electrostatic potential surface, may be responsible for the high toxicity of BmK M2.
PDB ID: 1CHZDownload
MMDB ID: 12895
PDB Deposition Date: 1999/3/31
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 1.76  Å
Source Organism:
Similar Structures:
Biological Unit for 1CHZ: monomeric; determined by author
Molecular Components in 1CHZ
Label Count Molecule
Protein (1 molecule)
1
Protein (Bmk M2)
Molecule annotation
Chemical (1 molecule)
1
1
* Click molecule labels to explore molecular sequence information.

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