Animal venoms are a rich and complex mixture of toxic and pharmacologically active proteins and peptides. Due to this broad range of biological functions, these biomolecules have been the subject of hundreds of scientific articles in different research fields, including biochemistry, biophysics, pharmacology, toxicology, and medicine.

Venoms from snakes of the family Viperidae contain class II PLA₂s, which share structural features with secretory PLA₂s of the class II-A present in inflammatory exudates in mammals. A number of venom PLA₂s have been shown to induce a variety of pharmacological effects although comprehensive studies of the actions of venom PLA₂s on the various events of toxicity are scarce. A particularly interesting subgroup of venom PLA₂s includes homologs having a number of amino acid substitutions at the calcium-binding loop, especially lysine substituting aspartate at position 49, resulting in the inability of these enzymes to bind calcium and, consequently, in the abrogation of their catalytic activity. Thus, these PLA₂s homologs exert their activities independently of enzymatic phospholipids degradation; the ability to induce pharmacological effects with higher potencies underscores the importance of PLA₂ enzymes in snake venom toxicity.

Today, despite a series of investigations in different areas, the mechanisms of action for both variants (D49 and K49 PLA₂ homologs) are not fully elucidated. We invite researchers to contribute original research articles and review articles and to encourage continued efforts to better understand the role of the catalytic activity and its absence in the homolog K49, in triggering drug events. Potential topics include, but are not limited to:

• Phospholipases A₂ and K49 homolog from snake venoms, emphasizing their biological activities in vivo and in vitro
• Studying calcium independence of snake venom phospholipases A₂ homologs (K49) pharmacologically based on the effects of synthetic peptides that identify a C-terminal region as being responsible for myotoxicity
• Studying the snake venom phospholipases A₂ as an antitumoral agent
• Perspective of snake venom PLA₂s, highlighting the variety of pharmacological activities associated with these enzymes and discussing the molecular regions involved in recognition of tissue targets
• Reviewing the use of chemical modifications in the study of venom PLA₂ and K49 homolog structure-function relationships