The modular nature of bradykinin-potentiating peptides isolated from snake venoms.

Bradykinin-potentiating peptides (BPPs) are molecules discovered by Sergio Ferreira - who found them in the venom of Bothrops jararaca in the 1960s - that literally potentiate the action of bradykinin in vivo by, allegedly, inhibiting the angiotensin-converting enzymes. After administration, the global physiological effect of BPP is the decrease of the blood pressure. Due to this interesting effect, one of these peptides was used by David Cushman and Miguel Ondetti to develop a hypotensive drug, the widely known captopril, vastly employed on hypertension treatment. From that time on, many studies on BPPs have been conducted, basically describing new peptides and assaying their pharmacological effects, mostly in comparison to captopryl. After compiling most of these data, we are proposing that snake BPPs are 'modular' peptidic molecules, in which the combination of given amino acid 'blocks' results in the different existing peptides (BPPs), commonly found in snake venom. We have observed that there would be mandatory modules (present in all snake BPPs), such as the N-terminal pyroglutamic acid and C-terminal QIPP, and optional modules (amino acid blocks present in some of them), such as AP or WAQ. Scattered between these modules, there might be other amino acids that would 'complete' the peptide, without disrupting the signature of the classical BPP. This modular arrangement would represent an important evolutionary advantage in terms of biological diversity that might have its origins either at the genomic or at the post-translational modification levels. Regardless of the modules' origin, the increase in the diversity of peptides has definitely been essential for snakes' success on nature.