This publication of 1981 presented a large and consistent body of work in which PLA2s of variable toxicity from the venoms of Naja nigricollis and N. naja atra (currently Naja atra) were chemically modified by carbamylation of lysine residues. When the modified toxins were tested on the different pharmacological systems, comparatively with native enzymes, a clear dissociation between enzymatic and pharmacological activities was observed, since toxicity was drastically reduced with this modification whereas enzymatic activity was decreased to a much lesser extent. These findings led support to the concept that pharmacoogical effects of some PLA2s may depend on a direct effect which does not correlate with the levels of phospholipid hydrolysis. It was argued that such direct effect may be related to the ability of toxic PLA2s to penetrate membranes. This contribution, and other related studies by this and other groups, paved the way for the concept that toxicity in venom PLA2s may be related to molecular regions, different from the catalytic site, that mediate interactions with critical targets in tissues. Once bound to relevant targets, enzymatic phospholipid hydrolysis may play a role in membrane damage and toxicity.