Isolation and biochemical characterization of bradykinin-potentiating peptides from Bitis gabonica rhinoceros

Abstract

BackgroundVenoms represent a still underexplored reservoir of bioactive components that might mitigate or cure diseases in conditions in which conventional therapy is ineffective. The bradykinin-potentiating peptides (BPPs) comprise a class of angiotensin-I converting enzyme (ACE) inhibitors. The BPPs usually consist of oligopeptides with 5 to 13 residues with a high number of proline residues and the tripeptide Ile-Pro-Pro (IPP-tripeptide) in the C-terminus region and have a conserved N-terminal pyroglutamate residue. As a whole, the action of the BPPs on prey and snakebite victims results in the decrease of the blood pressure. The aim of this work was to isolate and characterize novel BPPs from the venom of Bitis gabonica rhinoceros.MethodsThe crude venom of B. g. rhinoceros was fractionated by size exclusion chromatography and the peptide fraction (<7 kDa) was separated by reverse phase chromatography (RP-HPLC) and analyzed by ESI-IT-TOF-MS/MS. One new BPP was identified, synthetized and assayed for ACE inhibition and, in vivo, for edema potentiation.ResultsTypical BPP signatures were identified in three RP-HPLC fractions. CID fragmentation presented the usual y-ion of the terminal P-P fragment as a predominant signal at m/z 213.1. De novo peptide sequencing identified one Bothrops-like BPP and one new BPP sequence. The new BPP was synthesized and showed poor inhibition over ACE, but displayed significant bradykinin-induced edema potentiation.ConclusionsSo far, few BPPs are described in Viperinae, and based on the sequenced peptides, two non-canonical sequences were detected. The possible clinical role of this new peptides remains unclear.

<em>De Novo </em>Venom Gland Transcriptome Assembly and Characterization for <em>Calloselasma rhodostoma</em> (Kuhl, 1824), the Malayan Pit Viper from Malaysia: Unravelling Toxin Gene Diversity in a Medically Important Basal Crotaline

“…Bradykinin-potentiating peptides (BPPs) and C-type NPs (CNPs) are two well-characterized vasoactive blood pressure-modulating snake toxins found especially among pit vipers [69]. The occurrence of these peptides is mostly based on findings from cDNA sequencing, transcriptomics or genomics (e.g., Bothrops jararaca, Trimeresurus flavoviridis, Trimeresurus gramineus and Agkistrodon halys blomhoffi [71]; Bothrops jararaca [72]), while detection at the protein level has been scarce, presumably due to the peptides' low abundances and small molecular sizes that curtail detection (e.g., Trimeresurus flavoviridis [73]; Bitis gabonica rhinoceros [74]). The present study identified a substantial level of BPP/ACEI-CNP transcripts in the C. rhodostoma transcriptome (16.3% of all toxin FPKM), with homolog sequences matched to a multi-domain gene (UniProtKB: M5A7D0) coding for a BPP/ACEI-CNP precursor derived from a Thai specimen (Figure 6).…”

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

“…BPP 13d seems to have duplicated this modular insertion: <EGRAPHPPIPPAP. Moreover, a very interesting new BPP isolated from Bitis gabonica rhinoceros (APQERGPPEIPP) is, so far, the sole BPP with the -AP- module at the N-terminal [ 22 – 25 ].…”