Vol.:(0123456789) 1 3 Journal of Thrombosis and Thrombolysis https://doi.org/10.1007/s11239-018-1763-6 Carbon monoxide inhibits the anticoagulant activity of phospholipase A 2 purifed from Crotalus adamanteus venom Vance G. Nielsen 1 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Snake venom contains a myriad of classes of enzyme which have been investigated for medicinal and toxinological pur- poses, including phospholipase A 2 (PLA 2 ), which is responsible for anticoagulant, myotoxic and neurotoxic efects. Given the importance of PLA 2 , the purposes of the present investigation were to characterize the coagulation kinetic behavior of a PLA 2 purifed from Crotalus adamanteus venom (Ca-PLA 2 ) in human plasma with thrombelastography and determine if carbon monoxide could inhibit its activity. Coagulation kinetics were determined in human plasma with a range of Ca-PLA 2 activity (0–2 U/ml) via thrombelastography. Then, using carbon monoxide releasing molecule-2 or its inactivated molecule (0 or 100 µM), the vulnerability of Ca-PLA 2 activity to carbon monoxide mediated inhibition was assessed. Lastly, the inhibitory response of Ca-PLA 2 activity to exposure to carbon monoxide releasing molecule-2 (0–100 µM) was determined. Ca-PLA 2 activity degraded the velocity of clot growth and clot strength in an activity dependent, exponential manner. Carbon monoxide inhibited Ca-PLA 2 activity in a concentration dependent fashion, with loss of detectable activity at 100 µM of carbon monoxide releasing molecule-2. These fndings, while preliminary, open the possibility that other PLA 2 contained in snake venom with multiple toxicities (e.g., myotoxin, neurotoxin) may be heme bearing and CO-inhibitable, which have profound potential basic and clinical science implications. Keywords Carbon monoxide · Phospholipase A 2  · Thrombelastography · Anticoagulation Highlights • Snake venom phospholipase A 2 enzymes (PLA 2 ) play key roles in infammation and toxicity. • PLA 2 are involved in processes such as local tissue destruction and neuromuscular blockade causing respira- tory arrest. • Using thrombelastography, it was demonstrated that car- bon monoxide inhibited a PLA 2 derived from the Eastern diamondback rattlesnake. • Vulnerability to carbon monoxide inhibition is the sine qua non of heme bearing enzymes. • If these preliminary observations are broadly applicable, then they have profound potential implications concern- ing the investigation and management of PLA 2 toxicity. Introduction Snake venom contains a myriad of hemostatically active enzymes and proteins which have been investigated for medicinal and toxinological purposes [1]. These proteins may be procoagulant in nature, directly or indirectly acti- vating thrombin or via thrombin-like activity; conversely, venom can contain proteins that infict an anticoagulant efect by inhibiting platelet activity, destroying coagulation proteins, or degrading lipids critical to thrombin generation [1]. One particularly important type of snake venom enzyme is phospholipase A 2 (PLA 2 ), which is responsible for antico- agulant, myotoxic and neurotoxic efects [2]. PLA 2 are cal- cium-dependent and hydrolyze glycerophospholipids at the sn-2 position of the glycerol backbone, freeing fatty acids and lysophospholipids [2], such as those found in plasma * Vance G. Nielsen vgnielsen333@gmail.com 1 Department of Anesthesiology, The University of Arizona College of Medicine, 1501 North Campbell Avenue, P.O. Box 245114, Tucson, AZ 85724-5114, USA