Effects of Heme Modulation on Ovophis and Trimeresurus Venom Activity in Human Plasma

Abstract

Geographic isolation and other factors result in evolution-driven diversity of the enzymatic composition of venom of pit vipers in the same genus. The present investigation sought to characterize venoms obtained from such genetically diverse Ovophis and Trimeresurus pit vipers utilizing thrombelastographic coagulation kinetic analyses. The coagulation kinetics of human plasma were assessed after exposure to venom obtained from two Ovophis and three Trimeresurus species. The potency of each venom was defined (µg/mL required to equivalently change coagulation); additionally, venoms were exposed to carbon monoxide (CO) or a metheme-inducing agent to modulate any enzyme-associated heme. All venoms had fibrinogenolytic activity, with four being CO-inhibitable. While Ovophis venoms had similar potency, one demonstrated the presence of a thrombin-like activity, whereas the other demonstrated a thrombin-generating activity. There was a 10-fold difference in potency and 10-fold different vulnerability to CO inhibition between the Trimeresurus species. Metheme formation enhanced fibrinogenolytic-like activity in both Ovophis species venoms, whereas the three Trimeresurus species venoms had fibrinogenolytic-like activity enhanced, inhibited, or not changed. This novel “venom kinetomic” approach has potential to identify clinically relevant enzymatic activity and assess efficacy of antivenoms between genetically and geographically diverse species.

Mechanisms Responsible for the Anticoagulant Properties of Neurotoxic Dendroaspis Venoms: A Viscoelastic Analysis

“…The pattern of Dendroaspis-venom-mediated anticoagulation is consistent with SVMPs that are fibrinogenolytic, similar to other venoms containing fibrinogenolytic enzymes, wherein TMRTG values may not change, increase a small amount, or by a very great deal compared to plasma without venom addition; MRTG values that always are diminished; and TTG values that are diminished [21][22][23]. The variability in TMRTG is best explained by likely differences in plasma fibrinogen concentration following SVMP enzymatic action, as the time to commencement of clot formation is maintained until fibrinogen concentrations are very small, whereas MRTG and TTG values diminish rapidly with changes in fibrinogen concentrations, as has been documented in human plasma via thrombelastography [24].…”

Ruthenium, Not Carbon Monoxide, Inhibits the Procoagulant Activity of Atheris, Echis, and Pseudonaja Venoms

“…The key element of the paradigm that implicates CO as the mechanism behind the effects of CORMs is the determination that the inactivated releasing molecule (iRM), the portion of the CORM that remains after CO release, has no effect or a different effect on the system tested with the CORM compared to the anticipated CO effect. This laboratory has used this CORM-based paradigm for the past few years to demonstrate that CO inhibited the various procoagulant and anticoagulant activities of hemotoxic venoms and enzymes collected from dozens of snake and lizard species [1][2][3][4][5][6][7][8][9][10][11][12][13]. The particular CORM used was CORM-2 (tricarbonyldichlororuthenium (II) dimer) [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

“…This laboratory has used this CORM-based paradigm for the past few years to demonstrate that CO inhibited the various procoagulant and anticoagulant activities of hemotoxic venoms and enzymes collected from dozens of snake and lizard species [1][2][3][4][5][6][7][8][9][10][11][12][13]. The particular CORM used was CORM-2 (tricarbonyldichlororuthenium (II) dimer) [1][2][3][4][5][6][7][8][9][10][11][12][13]. The presumed mechanism was that CO must be interacting with a cryptic heme group attached to the various venoms and enzymes or in some other way interacting with these diverse enzymes and venoms [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

“…The particular CORM used was CORM-2 (tricarbonyldichlororuthenium (II) dimer) [1][2][3][4][5][6][7][8][9][10][11][12][13]. The presumed mechanism was that CO must be interacting with a cryptic heme group attached to the various venoms and enzymes or in some other way interacting with these diverse enzymes and venoms [1][2][3][4][5][6][7][8][9][10][11][12][13]. Thus, this potentially heme-based, CO-modulated paradigm of snake venom activity seemed plausible with the aforementioned paradigm of CORM-CO release-inert iRM interactions with target molecules.…”

“…While it is unreasonable to reassess all previous venoms inhibited by CORM-2 to determine if a Ru-based radical rather than CO was mediating the inhibition [1][2][3][4][5][6][7][8][9][10][11][12][13], assessing a few representative venoms would be of benefit. To this end, three procoagulant venoms derived from diverse species from Africa and Australia were selected that have already been characterized as inhibited by CORM-2 but not by its iRM by this laboratory [8,10].…”