R.E. Hill and S.P. Mackessy. Characterization of venom (Duvernoy's secretion) from
twelve species of colubrid snakes and partial sequence of four venom proteins. Toxicon
XX, xx-yy, 2000. - Venomous colubrids, which include more than 700 snake species worldwide,
represent a vast potential source of novel biological compounds. The present study
characterized venom (Duvernoy's gland secretion) collected from twelve species of
opisthoglyphous (rear-fanged) colubrid snakes, an extremely diverse assemblage of
non-venomous to highly venomous snakes. Most venoms displayed proteolytic activity
(casein), though activity levels varied considerably. Low phosphodiesterase activity
was detected in several venoms (Amphiesma stolata, Diadophis punctatus, Heterodon
nasicus kennerlyi, H. n. nasicus and Thamnophis elegans vagrans), and acetylcholinesterase
was found in Boiga irregularis saliva and venom, but no venoms displayed hyaluronidase,
thrombin-like or kallikrein-like activities. High phospholipase A(2) (PLA(2)) activity
was found in Trimorphodon biscutatus lambda venom, and moderate levels were detected
in Boiga dendrophila and D. p. regalis venoms as well as B. dendrophila and H. n.
nasicus salivas. Non-reducing SDS-PAGE revealed 7-20 protein bands (3.5 to over 200
kD, depending on species) for all venoms analyzed, and electrophoretic profiles of
venoms were typically quite distinct from saliva profiles. Components from A. stolata,
Hydrodynastes gigas, Tantilla nigriceps and T. e. vagrans venoms showed protease activity
when run on gelatin zymogram gels. N-terminal protein sequences for three 26 kD venom
components of three species (H. gigas, H. torquata, T. biscutatus) and one 3.5 kD
component (T. nigriceps) were also obtained, and the 3.5 kD peptide showed apparent
sequence homology with human vascular endothelial growth factor; these data represent
the first sequences of colubrid venom components. Protease, phosphodiesterase and
PLA(2) activities are also common to elapid and viperid snake venoms, but it is apparent
that numerous other (as yet undescribed) components make up the majority of colubrid
venom proteins. The complex nature of venoms produced by most species surveyed, and
the high levels of protease or phospholipase A(2) activity of some venoms, suggest
that many colubrids could become an important source of human health concern as encounters
with these snakes increase.