Background:
Snake venom has become a key source of many bioactive peptides, enzymes,
and toxins associated with blood coagulation and neuronal toxicity. In the past, a number
of bradykinin potentiating peptides have been isolated from snake venom that display hypotensive
activity due to their inhibitory action towards Angiotensin-Converting Enzyme (ACE). Significant
interest has developed to isolate, characterize, and subsequently design peptide analogs as potent
ACE-inhibitors which may find therapeutic applications for the treatment of hypertension and associated
diseases.
Aim:
The aim of this study is to search for new bioactive peptide/s in the venom of the snake Bothrops
Jararaca (Bj).
Objective:
The objective is to isolate and characterize new hypotensive peptides from BJ venom.
Methods:
We examined the venom of Bj which is known to host a range of bioactive peptides.
We have isolated a new peptide (BJ-1) which displayed in vitro potent hypotensive activity. The
peptide was purified via Sephadex G25 column chromatography and RP-HPLC. It was characterized
by mass spectrometry, amino acid analysis, N-terminal sequencing, and chemical synthesis.
Result:
The peptide was identified as an octa-decapeptide with amino acid sequence as DCPSDWSSYEGHCYKPFS
where the two Cys residues are likely present in free state, although they
can form an internal S-S bond upon oxidation. It was fully confirmed by comparing with synthetic
peptide prepared by solid phase chemistry. Both have the same molecular mass (2,108 Da) and
identical bioactivity. Furthermore, we rationalize that BJ-1 may be derived from precursor protein
“Coagulation factor IX/factor X binding protein (CF-IX/X-BP)” by proteolytic cleavage at the Nterminus
of its B-chain within the sequence KPFS18↓E19PKN. This cleavage site contains the recognition
motif of enzyme PCSK8 (Proprotein Convertase Subtilisin Kexin8) also known as Subtilisin
Kexin Isozyme 1 (SKI-1) or Site 1 Protease (S1P). Despite this observation, using a synthetic
peptide encompassing the proposed cleavage site and recombinant PCSK8 enzyme, we found that
the enzyme responsible for generation of BJ-1 is not PCSK8. Further studies will be needed to
identify the associated enzyme and fully characterize the pharmacological and biological properties
of the peptide.
Conclusion:
Our study revealed the presence of a novel hypotensive octa-decapeptide in the venom
of the snake Bothrops jararaca. It is likely derived from the A-chain of protein CF-IX/X-BP
via proteolytic cleavage at the N-terminus by a protease yet to be characterized.
