Structural analysis of Huwentoxin-I (1QK6), a neurotoxic peptide isolated from the venom of the Chinese bird spider Selenocosmia huwena [Qu et al., 1997] shows a structural feature of three disulfide bridges and three beta-strands. Sequence alignment and structure superposition of 1HWT with seven other peptides including funnel web spider toxin, cono-toxin and sweet taste repressor confirms that the core of this small folding unit is an anti-parallel beta-sheet and three disulfide bridges. This motif is one of the smallest folding unit belongs to the cystine-knot super family [Pallaghy et al., 1994; Harrison et al., 1996]. The connectivity of three disulfide bridges remains the same despite of the variation of sequence length and similarity. Careful comparison of our anti-fungal peptide against these 8 peptides implies that AFP may belong to this folding unit. A three dimensional model of AFP was constructed based on the above assumption.
The modeling work was carried out at the Biomolecular Modeling Laboratory, Imperial Cancer Research Fund by a Royal Society project to J LUO. Fig. 1 and Fig. 2 were generated by the molecular graphics program PREPI [Islam, 1998]. Thanks to Dr Gert Vriend and Dr Michael Sternberg for helpful discussion.
