Carbon monoxide inhibits the anticoagulant activity of phospholipase A2 purified from Crotalus adamanteus venom

Snake venom contains a myriad of classes of enzyme which have been investigated for medicinal and toxinological purposes, including phospholipase A(2) (PLA(2)), which is responsible for anticoagulant, myotoxic and neurotoxic effects. Given the importance of PLA(2), the purposes of the present investigation were to characterize the coagulation kinetic behavior of a PLA(2) purified 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 (0-2U/ml) via thrombelastography. Then, using carbon monoxide releasing molecule-2 or its inactivated molecule (0 or 100 mu M), 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 mu M) 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 mu M of carbon monoxide releasing molecule-2. These findings, 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.