Fig 1.
The number of NOEs per residue.
In this chart the intra-residue, sequential, medium range and long range NOEs are determined in different compartments and respectively shown in black, dark gray, light grey, and white.
Fig 2.
At the top, the schematic view of predicted secondary structure motifs of PPTI, and the sequence of its amino acid residues are shown. The observed sequential NOEs and the 3JHN-Hα coupling constants that are used in structure calculation are respectively shown with open and filled squares. For sequential NOEs, in case of proline residues, HN refers to Hδ that was used for the sequential assignments. At the bottom, the chart of chemical shift deviations of Cα that were calculated with respect to random chemical shift values is presented.
Fig 3.
The ensemble of top twenty superimposed PPTI NMR structures.
The structures are fitted to the best energetic one over the backbone atoms and the three intra-chain disulfide bonds are represented in sticks.
Fig 4.
The relative solvent accessibility of PPTI residues.
For each residue, the averaged value of relative accessible surface area (RASA) are calculated for the best twenty NMR structures. Both upper and lower limits that used for defining buried and solvent exposed residues are shown with dashed lines.
Fig 5.
The modeled structure of trypsin-PPTI complex fitted to its template (trypsin-BPTI complex).
On the right side, the close view of trypsin active site (S1 pocket) and anti-protease loop of both BPTI and PPTI are shown. The possible hydrogen bond and electrostatic interactions between labeled residues are shown by dashed lines.
Fig 6.
The modeled complex of PPTI and human Kv1.1 potassium channel.
(A) The side view of the complex. The critical residue of PPTI (K5) and its orientation towards the pore region is labeled. The water molecule at the pore entry is shown as a green sphere. (B) The top view of the complex. The negative electrostatic surface potential of Kv1.1 is shown in red. (C) The top view of the best energetically modeled complexes between PPTI and human Kv1.1 potassium channel.
Fig 7.
The electrostatic isocontour potential map and the surface potential of PPTI.
The blue and red colors represent positive and negative fields respectively. The electric dipole moment vector of the protein is represented as a green arrow and the proposed critical basic residue of dendrotoxin activity (K5) is labeled.