Structure and effects of a kinin potentiating fraction F (AppF) isolated from Agkistrodon piscivorus piscivorus venom

Exploring the Potential of Bioactive Peptides: From Natural Sources to Therapeutics

Bioactive peptides, specific protein fragments with positive health effects, are gaining traction in drug development for advantages like enhanced penetration, low toxicity, and rapid clearance. This comprehensive review navigates the intricate landscape of peptide science, covering discovery to functional characterization. Beginning with a peptidomic exploration of natural sources, the review emphasizes the search for novel peptides. Extraction approaches, including enzymatic hydrolysis, microbial fermentation, and specialized methods for disulfide-linked peptides, are extensively covered. Mass spectrometric analysis techniques for data acquisition and identification, such as liquid chromatography, capillary electrophoresis, untargeted peptide analysis, and bioinformatics, are thoroughly outlined. The exploration of peptide bioactivity incorporates various methodologies, from in vitro assays to in silico techniques, including advanced approaches like phage display and cell-based assays. The review also discusses the structure-activity relationship in the context of antimicrobial peptides (AMPs), ACE-inhibitory peptides (ACEs), and antioxidative peptides (AOPs). Concluding with key findings and future research directions, this interdisciplinary review serves as a comprehensive reference, offering a holistic understanding of peptides and their potential therapeutic applications.

A new structurally atypical bradykinin-potentiating peptide isolated from Crotalus durissus cascavella venom (South American rattlesnake)

Venom glands of some snakes synthesize bradykinin-potentiating peptides (BPP's) which increase bradykinin-induced hypotensive effect and decrease angiotensin I vasopressor effect by angiotensin-converting enzyme (ACE) inhibition. The present study shows a new BPP (BPP-Cdc) isolated from Crotalus durissus cascavella venom: Pro-Asn-Leu-Pro-Asn-Tyr-Leu-Gly-Ile-Pro-Pro. Although BPP-Cdc presents the classical sequence IPP in the C-terminus, it has a completely atypical N-terminal sequence, which shows very low homology with all other BPPs isolated to date. The pharmacological effects of BPP-Cdc were compared to BBP9a from Bothrops jararaca and captopril. BPP-Cdc (1 μM) significantly increased BK-induced contractions (BK; 1 μM) on the guinea pig ileum by 267.8% and decreased angiotensin I-induced contractions (AngI; 10 nM) by 62.4% and these effects were not significantly different from those of BPP9a (1 μM) or captopril (200 nM). Experiments with 4-week hypertensive 2K-1C rats show that the vasopressor effect of AngI (10 ng) was decreased by 50 μg BPP-Cdc (69.7%), and this result was similar to that obtained with 50 μg BPP9a (69.8%). However, the action duration of BPP-Cdc (60 min) was 2 times greater than that of BPP-9a (30 min). On the other hand, the hypotensive effect of BK (250 ng) was significantly increased by 176.6% after BPP-Cdc (50 μg) administration, value 2.5 times greater than that obtained with BPP9a administered at the same doses (71.4%). In addition, the duration of the action of BPP-Cdc (120 min) was also at least 4 times greater than that of BPP-9a (30 min). Taken together, these results suggest that BPP-Cdc presents more selective action on arterial blood system than BPP9a. Besides the inhibition of ACE, it may present other mechanisms of action yet to be elucidated.

Quantitative high-throughput profiling of snake venom gland transcriptomes and proteomes (Ovophis okinavensis and Protobothrops flavoviridis)

Background

Advances in DNA sequencing and proteomics have facilitated quantitative comparisons of snake venom composition. Most studies have employed one approach or the other. Here, both Illumina cDNA sequencing and LC/MS were used to compare the transcriptomes and proteomes of two pit vipers, Protobothrops flavoviridis and Ovophis okinavensis, which differ greatly in their biology.

Results

Sequencing of venom gland cDNA produced 104,830 transcripts. The Protobothrops transcriptome contained transcripts for 103 venom-related proteins, while the Ovophis transcriptome contained 95. In both, transcript abundances spanned six orders of magnitude. Mass spectrometry identified peptides from 100% of transcripts that occurred at higher than contaminant (e.g. human keratin) levels, including a number of proteins never before sequenced from snakes. These transcriptomes reveal fundamentally different envenomation strategies. Adult Protobothrops venom promotes hemorrhage, hypotension, incoagulable blood, and prey digestion, consistent with mammalian predation. Ovophis venom composition is less readily interpreted, owing to insufficient pharmacological data for venom serine and metalloproteases, which comprise more than 97.3% of Ovophis transcripts, but only 38.0% of Protobothrops transcripts. Ovophis venom apparently represents a hybrid strategy optimized for frogs and small mammals.

Conclusions

This study illustrates the power of cDNA sequencing combined with MS profiling. The former quantifies transcript composition, allowing detection of novel proteins, but cannot indicate which proteins are actually secreted, as does MS. We show, for the first time, that transcript and peptide abundances are correlated. This means that MS can be used for quantitative, non-invasive venom profiling, which will be beneficial for studies of endangered species.

A novel physiological property of snake bradykinin-potentiating peptides-reversion of MK-801 inhibition of nicotinic acetylcholine receptors

The first naturally occurring angiotensin-converting enzyme (ACE) inhibitors described are pyroglutamyl proline-rich oligopeptides, found in the venom of the viper Bothrops jararaca, and named as bradykinin-potentiating peptides (BPPs). Biochemical and pharmacological properties of these peptides were essential for the development of Captopril, the first active site-directed inhibitor of ACE, currently used for the treatment of human hypertension. However, a number of data have suggested that the pharmacological activity of BPPs could not only be explained by their inhibitory action on enzymatic activity of somatic ACE. In fact, we showed recently that the strong and long-lasting anti-hypertensive effect of BPP-10c [<ENWPHPQIPP] is independent of somatic ACE inhibition. On the other hand, nicotinic acetylcholine receptors expressed in blood vessels have been related to blood pressure regulation. Therefore, we have studied the effects of BPP-10c on acetylcholine receptor function in the PC12 pheochromocytoma cell line, which following induction to neuronal differentiation expresses most of the nicotinic receptor subtypes. BPP-10c did not induce receptor-mediated ion flux, nor potentiated carbamoylcholine-provoked receptor activity as determined by whole-cell recording. This peptide, however, alleviated MK-801-induced inhibition of nicotinic acetylcholine receptor activity. Although more data are needed for understanding the mechanism of the BPP-10c effect on nicotinic receptor activity and its relationship with the anti-hypertensive activity, this work reveals possible therapeutic applications for BPP-10c in establishing normal acetylcholine receptor activity.

A novel bradykinin potentiating peptide isolated from Bothrops jararacussu venom using catallytically inactive oligopeptidase EP24.15

Characterization of the peptide content of venoms has a number of potential benefits for basic research, clinical diagnosis, development of new therapeutic agents, and production of antiserum. Here, we use a substrate-capture assay that employs a catalytically inactive mutant of thimet oligopeptidase (EC 3.4.24.15; EP24.15) to identify novel bioactive peptides in Bothrops jararacussu venom. Of the peptides captured with inactive EP24.15 and identified by mass spectrometry, three were previously identified bradykinin-potentiating peptides (BPP), <ENWPHPQIPP (Xc), <EGGWPRPGPEIPP (XIIIa) and <EARPPHPPIPP (XIe) (where <E is a pyroglutamyl residue). In addition, we identified a novel BPP peptide containing additional AP amino acids in the C-terminus (<EARPPHPPIPPAP); this novel peptide was named BPP-AP. Next, dermal and muscle microcirculations were visualized using intravital microscopy to establish the roles of peptides BPP-XIe and BPP-AP in this process. After local administration of peptide BPP-XIe (0.5 microg.microL(-1)), leukocyte rolling flux and adhesion were increased by fivefold in post-capillary venules, without any increments in vasodilatation of arterioles compared to control experiments. In contrast, local administration of BPP-AP (0.5 microg.microL(-1)) potently induced vasodilatation of arterioles (nearly 100% increase compared with the vehicle saline control), with only a small increase in leukocyte rolling flux. Therefore, the novel BPP-AP described herein has pharmacological advantages compared to the BPP-XIe. The present study further suggests that inactive oligopeptidase EP24.15 is a useful tool for the isolation of bioactive peptides from crude biological samples.

Isolation and characterization of a novel bradykinin potentiating peptide (BPP) from the skin secretion of Phyllomedusa hypochondrialis

Bradykinin potentiating peptides (BPPs) from Bothrops jararaca venom were first described in the middle of 1960s and were the first natural inhibitors of the angiotensin-converting enzyme (ACE). BPPs present a classical motif and can be recognized by their typical pyroglutamyl (Pyr)/proline rich sequences presenting, invariably, a proline residue at the C-terminus. In the present study, we describe the isolation and biological characterization of a novel BPP isolated from the skin secretion of the Brazilian tree-frog Phyllomedusa hypochondrialis. This new BPP, named Phypo Xa presents the sequence Pyr-Phe-Arg-Pro-Ser-Tyr-Gln-Ile-Pro-Pro and is able to potentiate bradykinin activities in vivo and in vitro, as well as efficiently and competitively inhibit ACE. This is the first canonical BPP (i.e. Pyr-Aaa(n)-Gln-Ile-Pro-Pro) to be found not only in the frog skin but also in any other natural source other than the snake venoms.

A novel peptide from the ACEI/BPP-CNP precursor in the venom of Crotalus durissus collilineatus

In crotaline venoms, angiotensin-converting enzyme inhibitors [ACEIs, also known as bradykinin potentiating peptides (BPPs)], are products of a gene coding for an ACEI/BPP-C-type natriuretic peptide (CNP) precursor. In the genes from Bothrops jararaca and Gloydius blomhoffii, ACEI/BPP sequences are repeated. Sequencing of a cDNA clone from venom glands of Crotalus durissus collilineatus showed that two ACEIs/BPPs are located together at the N-terminus, but without repeats. An additional sequence for CNP was unexpectedly found at the C-terminus. Homologous genes for the ACEI/BPP-CNP precursor suggest that most crotaline venoms contain both ACEIs/BPPs and CNP. The sequence of ACEIs/BPPs is separated from the CNP sequence by a long spacer sequence. Previously, there was no evidence that this spacer actually coded any expressed peptides. Aird and Kaiser (1986, unpublished) previously isolated and sequenced a peptide of 11 residues (TPPAGPDVGPR) from Crotalus viridis viridis venom. In the present study, analysis of the cDNA clone from C. d. collilineatus revealed a nearly identical sequence in the ACEI/BPP-CNP spacer. Fractionation of the crude venom by reverse phase HPLC (C(18)), and analysis of the fractions by mass spectrometry (MS) indicated a component of 1020.5 Da. Amino acid sequencing by MS/MS confirmed that C. d. collilineatus venom contains the peptide TPPAGPDGGPR. Its high proline content and paired proline residues are typical of venom hypotensive peptides, although it lacks the usual N-terminal pyroglutamate. It has no demonstrable hypotensive activity when injected intravenously in rats; however, its occurrence in the venoms of dissimilar species suggests that its presence is not accidental. Evidence suggests that these novel toxins probably activate anaphylatoxin C3a receptors.

Hypothesized and found mechanisms for potentiation of bradykinin actions

Potentiation of hormone actions can occur by different mechanisms, including inhibition of degrading enzymes, interaction with the hormone receptor leading to stabilization of bioactive conformation or leading to receptor homo- and hetero-oligomerization, receptor phosphorylation and dephosphorylation or can occur by directly influencing the signal transduction and ion channels. In this review the potentiation of bradykinin actions in different systems by certain compounds will be reviewed. Despite many long years of experimental research and investigation the mechanisms of potentiating action remain not fully understood. One of the most contradictory findings are the distinct differences between the inhibition of the angiotensin I-converting enzyme and the potentiation of the bradykinin induced smooth muscle reaction. Contradictory findings and hypothesized mechanisms in the literature are discussed in this review and in some cases compared to own results. Investigation of potentiating actions was extended from hypotension, smooth muscle reaction and cellular actions to activation of immunocompetent cells. In our opinion the potentiation of bradykinin action can occur by different mechanisms, depending on the system and the applied potentiating factor used.

Potentiation of bradykinin actions by analogues of the bradykinin potentiating nonapeptide BPP9alpha

Synthetic analogues of the bradykinin potentiating nonapeptide BPP9alpha indicate significantly different structural requirements for potentiation of the bradykinin (BK)-induced smooth muscle contraction (GPI) and the inhibition of isolated somatic angiotensin I-converting enzyme (ACE). The results disprove the ACE inhibition as the only single mechanism and also the direct interaction of potentiating peptides with the bradykinin receptors in transfected COS-7 cells as molecular mechanism of potentiation. Our results indicate a stimulation of inositol phosphates (IPn) formation independently from the B2 receptor. Furthermore, the results with La3+ support the role of extracellular Ca2+ and its influx through corresponding channels. The missing effect of calyculin on the GPI disproves the role of phosphatases in the potentiating action. These experimental studies should not only contribute to a better understanding of the potentiating mechanisms but also incorporate a shift in the research towards the immune system, in particular towards the immunocompetent polymorphonuclear leukocytes. The chemotaxis of these cells can be potentiated most likely by exclusive inhibition of the enzymatic degradation of bradykinin. Thus the obtained results give evidence that the potentiation of the bradykinin action can occur by different mechanisms, depending on the system and on the applied potentiating factor.

Identification of five new bradykinin potentiating peptides (BPPs) from Bothrops jararaca crude venom by using electrospray ionization tandem mass spectrometry after a two-step liquid chromatography

Bradykinin potentiating peptides (BPPs) from Bothrops jararaca venom were described in the middle of 1960s and were the first natural inhibitors of the angiotensin-converting enzyme displaying strong anti-hypertensive effects in human subjects. The BPPs can be recognized by their typical pyroglutamyl proline-rich oligopeptide sequences presenting invariably a proline residue at the C-terminus. In the present study, we identified 18 BPPs, most of them already described for the B. jararaca venom. We isolated and sequenced new peptides ranging from 5 to 14 amino acid residues exhibiting similar amino acid sequence features. The applied methodology consisted of a strait two-step liquid chromatography, followed by mass spectrometry analysis. Besides the amino acid sequence homology, the corresponding synthetic peptides were able to potentiate bradykinin on the isolated guinea-pig ileum.

Pharmacology and biochemistry of spider venoms

Spider venoms represent an incredible source of biologically active substances which selectively target a variety of vital physiological functions in both insects and mammals. Many toxins isolated from spider venoms have been invaluable in helping to determine the role and diversity of neuronal ion channels and the process of exocytosis. In addition, there is enormous potential for the use of insect specific toxins from animal sources in agriculture. For these reasons, the past 15-20 years has seen a dramatic increase in studies on the venoms of many animals, particularly scorpions and spiders. This review covers the pharmacological and biochemical activities of spider venoms and the nature of the active components. In particular, it focuses on the wide variety of ion channel toxins, novel non-neurotoxic peptide toxins, enzymes and low molecular weight compounds that have been isolated. It also discusses the intraspecific sex differences in given species of spiders.

cDNA cloning of bradykinin-potentiating peptides-C-type natriuretic peptide precursor, and characterization of the novel peptide Leu3-blomhotin from the venom of Agkistrodon blomhoffi

A cDNA clone, 1.8 kb long, was isolated from a venom gland cDNA library of Agkistrodon blomhoffi that encodes a large plurifunctional precursor composed of 263 amino-acid residues. Nucleotide sequence analysis of this clone revealed that sequences which code for blomhotin and a novel peptide Leu3-blomhotin are located in the N-terminal region of the precursor polypeptide, followed by four tandemly aligned sequences which code for three types of bradykinin-potentiating peptide. In the C-terminal region, the sequence for the C-type natriuretic peptide was located along with a preceding processing signal. The deduced amino-acid sequences for the four bradykinin-potentiating peptides coincided exactly with previously known sequences for potentiator B, potentiator C and potentiator E. The actual Leu3-blomhotin peptide was subsequently isolated from the venom of A. blomhoffi and characterized. Leu3-blomhotin possesses contractile activity in isolated rat stomach fundus smooth muscle in the same manner as blomhotin. Furthermore, it was shown that blomhotin and Leu3-blomhotin retained activity to inhibit the angiotensin-converting enzyme.

Spatial structures of the bradykinin potentiating peptide F from Agkistrodon piscivorus piscivoris venom

Bradykinin potentiating peptides usually show two different activities, potentiation of bradykinin and inhibition of angiotensin converting enzyme (ACE). Exceptions of this rule have been found suggesting that both effects occur independently. This study of peptide F by means of NMR spectroscopy shows clearly two different main conformations of the molecule. These different conformations may be the reason for the different activities.

Isolation and characterization of a bradykinin potentiating peptide (BPP-S) isolated from Scaptocosa raptoria venom

Venom of the spider Scaptocosa raptoria was fractionated by chromatography on Sephadex G-10 followed by HPLC, and a bradykinin potentiating peptide, BPP-S, was obtained in pure form. The amino acid sequence of this undecapeptide is presented. Peptide BPP-S significantly potentiates the effects of bradykinin on smooth muscle, and inhibits the angiotensin-converting enzyme (ACE) in vitro.