1omb
From Proteopedia
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SEQUENTIAL ASSIGNMENT AND STRUCTURE DETERMINATION OF SPIDER TOXIN OMEGA-AGA-IVB
Overview
The solution structure of a peptide toxin isolated from funnel web spider, venom, omega-Aga-IVB, was determined by 2D NMR methods. omega-Aga-IVB is a, high-affinity specific blocker of P-type voltage-dependent calcium, channels. Nearly all of the proton resonances of this 48-residue protein, were assigned using conventional 2D homonuclear NMR experiments. The, three-dimensional structure of the molecule was determined by simulated, annealing. The distance and dihedral restraints used in the structure, calculations were derived from NOESY and COSY-type experiments, respectively. Mass spectrometric analysis of omega-Aga-IVB suggests that, the protein contains four disulfide bonds. In the absence of chemical data, to identify the pattern of cysteine pairing, the disulfide bonds of the, toxin are proposed from the NMR data and subsequent structural, calculations. The structure of the toxin can be described as a, three-stranded anti-parallel beta sheet connected by flexible loops. A, striking feature of the structure is that the C-terminal 10 residues of, this protein adopt random coil conformations. Several positively charged, amino acid side chains are found localized on one face of the molecule, in, close proximity to the C-terminal tail. This observation has led us to, propose a speculative model of the toxins blockade mechanism.
About this Structure
1OMB is a Single protein structure of sequence from Agelenopsis aperta. Full crystallographic information is available from OCA.
Reference
Sequential assignment and structure determination of spider toxin omega-Aga-IVB., Yu H, Rosen MK, Saccomano NA, Phillips D, Volkmann RA, Schreiber SL, Biochemistry. 1993 Dec 7;32(48):13123-9. PMID:8241166
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