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activity was detected in secretion from either
P. olfersii
or
P. patagoniensis
(da Rocha
and de Furtado, 2007). In contrast, Peichoto et al. (2005) reported potent fibrinogeno-
lytic activity in Duvernoy's secretion of
P. patagoniensis
. The activity was inhibited
by several chelating agents, such as ethylenediaminetetraacetic acid (EDTA), benza-
midine, and/or phenylmethylsulfonyl-flouride (PMSF). This suggested that the fibrino-
genolytic activity was due to metalloproteases and serine proteases (Peichoto et al.,
2005). This finding is supported by the previously reported fibrinogenolytic activity
and subsequent characterization from
P. olfersii
Duvernoy's secretion of four acidic
and one basic fibrinogenolytic proteases (one serine protease and four metalloprote-
ases) ranging in molecular mass between 36 and 58 kDa (Assakura et al., 1992, 1994).
One of the metalloproteases (“ProfibH”) also exhibited hemorrhagic activity (Assakura
et al., 1994). Similarly, an acidic 53.2-kDa α-fibrinogenolytic metalloprotease with
hemorrhagic activity (“patagonfibrase”) has been purified from Duvernoy's secretion
of
P. patagoniensis
(Peichoto et al., 2007a,b). Fibrinogenolytic metalloproteases can
directly cleave fibrinogen into fibrinopeptides A or B without producing a clot (
Figure
4.1
). This can potentially contribute to depletion of fibrinogen available for formation
of a fibrin clot via thrombin action (
Figure 4.1
). Thus, the presence of these enzymes
in
Philodryas
spp. Duvernoy's secretion could conceivably contribute to coagulopa-
thy from a bite by some of these snakes. Documentation of hemostatic laboratory tests
from verified cases of
Philodryas
bites is needed in order to confirm coagulopathic
envenomations by members of this genus.
Some of these contrasting findings may be due to variability in Duvernoy's secre-
tion components and/or ontogenetic variation, as has been demonstrated in secretion
from
B. irregularis
(Mackessy et al., 2006; Weinstein et al., 1993; see Section 4.5).
Conversely, experimental methods may lead to some incommensurability between
laboratories.
Similar to the avian- and saurian-specific toxins characterized from Duvernoy's
secretions of
B. dendrophila
and
B. irregularis
(see chapter 3), an avian-specific neu-
rotoxin has been detected in Duvernoy's secretion from
P. olfersii
(Prado-Franceschi
et al., 1996). In addition, an acidic, 182 amino acid myotoxin has been characterized
from the Duvernoy's secretion of this species (Prado-Franceschi et al., 1998), and a
24.858 kDa CRISP with myotoxic activity (“patagonin”) has been characterized from
Duvernoy's secretion of
P. patagoniensis
(Peichoto et al., 2009).
Several of the aforementioned investigators frequently compared the docu-
mented edematogenic, hemorrhagic, proteolytic, and/or necrotic activities detected
in
Philodryas
spp. Duvernoy's secretions to those of venoms from various
Bothrops
spp. (Acosta de Pérez et al., 2003; Assakura et al., 1992, 1994; Peichoto et al., 2005;
de Perez et al., 2003). It is noteworthy that de Pérez et al. (2003) estimated the edem-
atogenic activity of
P. olfersii
secretion from more than 3.5 to less than 10 times that
of venoms from four taxa of
Bothrops
spp. [
B. alternatus
(urutu or half-moon viper),
B. jararaca
(jararaca),
B. jararacussu
(jararacussu), and
B. neuwiedi (sensu lato
;
Neuwied's lance-headed viper); see
Plates 4.73-4.75
for representative
Bothrops
spp.].
