Potency optimization of Huwentoxin-IV on hNav1.7: A neurotoxin TTX-S sodium-channel antagonist from the venom of the Chinese bird-eating spider Selenocosmia huwena

Spider peptide toxin HwTx-IV engineered to bind to lipid membranes has an increased inhibitory potency at human voltage-gated sodium channel hNa V 1.7

“…Briefly, electrostatic interactions between gHwTx-IV and the membrane would attract the peptide to the membrane surface and additional hydrogen bonding and hydrophobic interactions would orient the peptide such that the face containing R26, K27 and K32 is available for interactions with hNa V 1.7 ( Figure 6). In addition, the overall decrease in anionic charge and increase in hydrophobicity of gHwTx-IV might further augment interactions between the peptide and hNa V 1.7 This hypothesis was previously proposed by Revell and colleagues [13], when the authors observed an increase in the inhibitory potency of the analogue [E1G,E4G,Y33W]HwTx-IV [21]. In silico docking studies suggested that the residues F6 and Y33 form hydrophobic interactions with M750 on hNa V 1.7; thus, a supporting explanation for the increased activity observed with gHwTx-IV is that the mutations F6W and…”

“…gHwTx-IV is a derivative of another HwTx-IV analogue: [E1G,E4G,Y33W]HwTx-IV, shown previously to have increased potency at hNa V 1.7 (IC 50 = 0.4 nM) compared to HwTx-IV (IC 50 = 27 nM) [21].…”

“…gHwTx-IV was dissolved in 50% v/v ACN prior to drop-wise addition to a buffer consisting of 0.1 M Tris-HCl, 10% v/v filtered isopropanol (pH 8), 5 mM reduced glutathione and 1 mM oxidized glutathione bringing the final peptide concentration to 0.05 mg/mL. The reaction was quenched by lowering the pH to pH 2 using ACN/TFA/water (1:1:1) (v/v/v) [21].…”

“…Furthermore, the fact the amino acid residues that seem to be involved in membrane binding are distinct from those involved in channel binding lead us to postulate that gHwTx-IV will show a similar selectivity profile to HwTx-IV, particularly against Na V 1.5 which is involved in cardiac muscle conduction [16]. This hypothesis is further supported by [E1G,E4G,Y33W]HwTx-IV, an analogue similar to gHwTx-IV, which was found to be inactive at Na V 1.5 [21].…”

Centipede venoms as a source of drug leads

“…The human subtypes often have distinctly different tissue distribution and physiological roles compared with insect Na V channels, and consequently venom peptides that evolved to paralyse/kill prey by targeting insect Na V channels can have therapeutic effects in mammals. For example, Amgen [81], AstraZeneca/MedImmune [82], Johnson & Johnson/Janssen [83], and Merck [84,85] have all examined the analgesic potential of spider-venom peptides that target the human Na V 1.7 (hNa V 1.7) channel.…”