Summary
Pm-VEGF, a novel member ofVEGF family from the venom gland of Taiwan habu (Protobothrops mucrosquamatu), is a disulfidelinked homodimer with 119 amino acid residues. Recombinant fusion
Pm-VEGF was expressed in Escherichia coli, purified and refolded. Surface plasmon resonance was used to determine its binding
kinetics toVEGF-receptors (VEGFR). Relative to human VEGF165, the binding affinity of Pm-VEGF to the VEGFR-1 was 1.7-fold higher while affinity
to the VEGFR-2 was 17-fold lower. But it did not bind theVEGFR-3 or neuropilin-1.
Pm-VEGF promoted the proliferation and tissue factor production of endothelial cells,
the neovascularization in the chicken chorioallantoic membrane, and increased vascular
permeability. It also stimulated tissue-factor production and human monocyte chemotaxis,
in accord with its specificity for VEGFR-1. Structural comparison among VEGF-proteins
from various viper venoms revealed that the two subfamilies of vipers (Crotalinae
and Viperinae) have evolved with distinct receptor-specificities for VEGFR-1 and VEGFR-2,
respectively. Discussion on structureactivity relationships of the VEGFs further provided
insight into residues important for the receptor-binding and specificities.
Keywords
Snake venom VEGF - receptor specificity - vascular permeability - angiogenesis - monocyte
chemotaxis