5'-nucleotidase family

General 5'-nucleotidases (EC 3.1.3.5) are enzymes that catalyze the hydrolysis of phosphate esterified at carbon 5' of the ribose and deoxyribose portions of nucleotide molecules. They are ubiquitous enzymes found in a wide variety of species and which occur in different cellular locations (Zimmermann, 1992 ).

Present in almost all snake venoms, however, their pharmacological activities are not well characterized. They are known to endogenously liberate purines (mainly adenosines), which act as multitoxins. Purines potentiate venom-induced hypotension and paralysis via purine receptors, which are ubiquitously distributed among various organisms envenomed by snakes. In addition, some reports also suggest other toxic nature of these enzymes either acting independently or synergistically with other toxin proteins, contributing to the overall lethal effects of venoms (Dhananjaya and D’Souza, 2010 ).