An overview on nucleases (DNase, RNase, and phosphodiesterase) in snake venoms

ISSN 0006 2979, Biochemistry (Moscow), 2010, Vol. 75, No. 1, pp. 1 6. Pleiades Publishing, Ltd., 2010. Published in Russian in Biokhimiya, 2010, Vol. 75, No. 1, pp. 5 11.

REVIEW

An Overview on Nucleases (DNase, RNase, and Phosphodiesterase) in Snake Venoms

B. L. Dhananjaya and C. J. M. DSouza*

Department of Studies in Biochemistry, University of Mysore, Manasagangothri, Mysore 570006, India; fax: [phone]; E mail: [email protected]

Received April 16, 2009 Revision received May 6, 2009

AbstractIn this review, we have compiled the data on pharmacological activities associated with endogenous purine release related enzymesnucleases (DNases, RNases, and phosphodiesterases). The results of studies on toxic effects of these enzymes, emphasizing the future directions in this field, are summarized. One of the major problems facing toxicologists is the identification and characterization of specific venom nucleases since they share similar substrate specificities and bio chemical properties. In this review, we have attempted to clarify some of the discrepancies about these enzymes. Further, we have tried to correlate the existence of nuclease enzymes in relation to endogenous release of purines, a multitoxin, during snake envenomation, and we also discuss the possible actions of purines. We hope that this review will stimulate renewed interest among toxicologists to biologically characterize these enzymes and elucidate their role in envenomation.

DOI: 10.1134/S0006297910010013

Key words: purines, DNase, RNase, phosphodiesterase, snake envenomation, adenosine

Snake venom is a complex mixture of biologically active components comprising hydrolytic enzymes, non enzymatic proteins/peptides, and small amounts of organ ic and inorganic molecules [1 3]. The venom components, known to vary with geographic location, season, and age of the snake [4 8], is not primarily for self defense, but has a more important role in prey immobilization and its subse quent digestion [2, 9 11]. Hence, several digestive enzymes in venoms, in addition to their hydrolytic activity, have evolved to interfere with diverse physiological processes that help in the immobilization of prey/victim [2, 12, 13]. For example, hydrolytic enzymes such as proteases and phospholipase A2 (PLA2) of snake venoms are known to induce both systemic and local effects. Several PLA2 enzymes are known to exhibit neurotoxicity (post /presy

naptic) and cardiotoxicity and are pro /anticoagulant, thereby interfering with hemostasis. PLA2 and proteases are responsible for local tissue damage and...