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1.
    
Somatostatin and its related peptides (SSRPs) form an important family of hormones with diverse physiological roles. The ubiquitous presence of SSRPs in vertebrates and several invertebrate deuterostomes suggests an ancient origin of the SSRP signaling system. However, the existence of SSRP genes outside of deuterostomes has not been established, and the evolutionary history of this signaling system remains poorly understood. Our recent discovery of SSRP-like toxins (consomatins) in venomous marine cone snails (Conus) suggested the presence of a related signaling system in mollusks and potentially other protostomes. Here, we identify the molluscan SSRP-like signaling gene that gave rise to the consomatin family. Following recruitment into venom, consomatin genes experienced strong positive selection and repeated gene duplications resulting in the formation of a hyperdiverse family of venom peptides. Intriguingly, the largest number of consomatins was found in worm-hunting species (>400 sequences), indicating a homologous system in annelids, another large protostome phylum. Consistent with this, comprehensive sequence mining enabled the identification of SSRP-like sequences (and their corresponding orphan receptor) in annelids and several other protostome phyla. These results established the existence of SSRP-like peptides in many major branches of bilaterians and challenge the prevailing hypothesis that deuterostome SSRPs and protostome allatostatin-C are orthologous peptide families. Finally, having a large set of predator–prey SSRP sequences available, we show that although the cone snail’s signaling SSRP-like genes are under purifying selection, the venom consomatin genes experience rapid directional selection to target receptors in a changing mix of prey.  相似文献   

2.
We report the first example of conopeptide oxidation performed in a biocompatible ionic liquid, 1‐ethyl‐3‐methylimidazolium acetate ([C2mim][OAc]), which enables the efficient formation of both hydrophilic and poorly water‐soluble conotoxins compared with conventional methods. Moreover, the method features a high‐concentration approach ultimately leading to higher yields at reduced separation effort. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

3.
    
Oxidative folding that occurs in a crowded cellular milieu is characterized by multifaceted interactions that occur among nascent polypeptides and resident components of the endoplasmic reticulum (ER) lumen. Macromolecular crowding has been considered an essential factor in the folding of polypeptides, but the excluded volume effect has not been evaluated for small, disulfide‐rich peptides. In the research presented, we examined how macromolecular crowding agents, such as albumin, ovalbumin, and polysaccharides, influenced the kinetics and thermodynamics of forming disulfide bonds in four model peptides of varying molecular size from 13 residues (1.4 kDa) to 58‐residues (6.5 kDa): conotoxins: GI, PVIIA, r11a, and bovine pancreatic trypsin inhibitor. Our results indicate that the excluded volume effect does not significantly alter the folding rates nor equilibria for these peptides. In stark contrast, folding reactions were dramatically accelerated, when protein‐based crowding agents were present at concentrations lower than those predicted to provide the excluded volume effect. Submillimolar albumin alone was as effective as glutathione in promoting the oxidative folding of GI conotoxin at concentrations typically found in the ER. To the best of our knowledge, this is the first report and quantitative characterization of oxidative folding of peptides mediated by other than thioredoxin‐based protein disulfide bonds. Our work raises a possibility that concurrent secretory and ER‐resident proteins may influence the oxidative folding of small, cysteine‐rich peptides not as crowding agents, but as redox‐active factors. © 2006 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88:8–19, 2007. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com.  相似文献   

4.
Over 200 components with molecular mass ranging mainly from 400 to 4000 Da were characterized from the venom of the vermivorous cone snail Conus fulgetrum that inhabit Egyptian Red Sea. One major component having a molecular mass of 2946 Da was purified by HPLC, and its primary structure was determined by a combination of Edman degradation and MS/MS analysis.  相似文献   

5.
    
The cyclic conotoxin analogue cVc1.1 is a promising lead molecule for the development of new treatments for neuropathic and chronic pain. The design of this peptide includes a linker sequence that joins the N and C termini together, improving peptide stability while maintaining the structure and activity of the original linear Vc1.1. The effect of linker length on the structure, activity and stability of cyclised conotoxins has been studied previously but the effect of altering the composition of the linker sequence has not been investigated. In this study, we designed three analogues of cVc1.1 with linker sequences that varied in charge, hydrophobicity and hydrogen bonding capacity and examined the effect on structure, stability, membrane permeability and biological activity. The three designed peptides were successfully synthesized using solid phase peptide synthesis approaches and had similar structures and stability compared with cVc1.1. Despite modifications in charge, hydrophobicity and hydrogen bonding potential, which are all factors that can affect membrane permeability, no changes in the ability of the peptides to pass through membranes in either PAMPA or Caco‐2 cell assay were observed. Surprisingly, modification of the linker sequence was deleterious to biological activity. These results suggest the linker sequence might be a useful part of the molecule for optimization of bioactivity and not just the physiochemical properties of cVc1.1. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 864–875, 2016.  相似文献   

6.
    
The oxidative folding of small, cysteine‐rich peptides to selectively achieve the native disulfide bond connectivities is critical for discovery and structure‐function studies of many bioactive peptides. As the propensity to acquire the native conformation greatly depends on the peptide sequence, numerous empirical oxidation methods are employed. The context‐dependent optimization of these methods has thus far precluded a generalized oxidative folding protocol, in particular for peptides containing more than two disulfides. Herein, we compare the efficacy of optimized solution‐phase and polymer‐supported oxidation methods using three disulfide‐bridged conotoxins, namely µ‐SIIIA, µ‐KIIIA and ω‐GVIA. The use of diselenide bridges as proxies for disulfide bridges is also evaluated. We propose the ClearOx‐assisted oxidation of selenopeptides as a fairly generalized oxidative folding protocol. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

7.
    
The disulfide bond pattern of catrocollastatin-C was determined by N-terminal sequencing and mass spectrometry. The N-terminal disintegrin-like domain is a compact structure including eight disulfide bonds, seven of them in the same pattern as the disintegrin bitistatin. The protein has two extra cysteine residues (XIII and XVI) that form an additional disulfide bond that is characteristically found in the disintegrin-like domains of cellular metalloproteinases (ADAMs) and PIII snake venom Zn-metalloproteinases (SVMPs). The C-terminal cysteine-rich domain of catrocollastatin-C contains five disulfide bonds between nearest-neighbor cysteines and a long range disulfide bridge between CysV and CysX. These results provide structural evidence for a redefinition of the disintegrin-like and cysteine-rich domain boundaries. An evolutionary pathway for ADAMs, PIII, and PII SVMPs based on disulfide bond engineering is also proposed.  相似文献   

8.
    
Chlorotoxin (CTX), a disulfide‐rich peptide from the scorpion Leiurus quinquestriatus , has several promising biopharmaceutical properties, including preferential affinity for certain cancer cells, high serum stability, and cell penetration. These properties underpin its potential for use as a drug design scaffold, especially for the treatment of cancer; indeed, several analogs of CTX have reached clinical trials. Here, we focus on its ability to internalize into cells—a trait associated with a privileged subclass of peptides called cell‐penetrating peptides—and whether it can be improved through conservative substitutions. Mutants of CTX were made using solid‐phase peptide synthesis and internalization into human cervical carcinoma (HeLa) cells was monitored by fluorescence and confocal microscopy. CTX_M1 (ie, [K15R/K23R]CTX) and CTX_M2 (ie, [K15R/K23R/Y29W]CTX) mutants showed at least a twofold improvement in uptake compared to CTX. We further showed that these mutants internalize into HeLa cells largely via an energy‐dependent mechanism. Importantly, the mutants have high stability, remaining intact in serum for over 24 h; thus, retaining the characteristic stability of their parent peptide. Overall, we have shown that simple conservative substitutions can enhance the cellular uptake of CTX, suggesting that such type of mutations might be useful for improving uptake of other peptide toxins.  相似文献   

9.
    
The broad‐spectrum activity of antimicrobial peptides (AMPs) and low probability of development of host resistance make them excellent candidates as novel bio‐control agents. A number of AMPs are found to be cationic, and a small proportion of these are tryptophan‐rich. The puroindolines (PIN) are small, basic proteins found in wheat grains with proposed roles in biotic defence of seeds and seedlings. Synthetic peptides based on their unique tryptophan‐rich domain (TRD) display antimicrobial properties. Bacterial endospores and biofilms are highly resistant cells, with significant implications in both medical and food industries. In this study, the cationic PIN TRD‐based peptides PuroA (FPVTWRWWKWWKG‐NH2) and Pina‐M (FSVTWRWWKWWKG‐NH2) and the related barley hordoindoline (HIN) based Hina (FPVTWRWWTWWKG‐NH2) were tested for effects on planktonic cells and biofilms of the common human pathogens including Pseudomonas aeruginosa, Listeria monocytogenes and the non‐pathogenic Listeria innocua. All peptides showed significant bactericidal activity. Further, PuroA and Pina‐M at 2 × MIC prevented initial biomass attachment by 85–90% and inhibited >90% of 6‐h preformed biofilms of all three organisms. However Hina, with a substitution of Lys‐9 with uncharged Thr, particularly inhibited Listeria biofilms. The PIN based peptides were also tested against vegetative cells and endospores of Bacillus subtilis. The results provided evidence that these tryptophan‐rich peptides could kill B. subtilis even in sporulated state, reducing the number of viable spores by 4 log units. The treated spores appeared withered under scanning electron microscopy. The results establish the potential of these tryptophan‐rich peptides in controlling persistent pathogens of relevance to food industries and human health. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

10.
    
Some antimicrobial peptides (AMPs) have been described to exert immunomodulatory effects, which may contribute to their in vivo antibacterial activity. Very recently, we could show that novel oncocin and apidaecin derivatives are potently antibacterially active in vivo. Therefore, we studied oncocin and apidaecin derivatives for their effects on murine dendritic cells (DC) and macrophages and compared them with well‐known immunomodulatory activities of murine cathelicidin‐related antimicrobial peptide (CRAMP). To characterize the immunomodulatory activity of the peptides on key cells of the innate immune system, we stimulated murine DC and macrophages with the oncocin and apidaecin derivatives alone, or in combination with lipopolysaccharide (LPS). We analyzed the secretion of pro‐inflammatory cytokines, the expression of surface activation markers, and the chemotactic activity of the AMPs. In contrast to LPS, none of the oncocin and apidaecin derivatives alone has an influence on cytokine or surface marker expression by DC and macrophages. Furthermore, the tested oncocin and apidaecin derivatives do not modulate the immune response after LPS stimulation, whereas CRAMP shows a reduction of the LPS‐mediated immune response as expected. All peptides tested are not chemotactic for DC. Together, lack of in vitro immunomodulatory effects by oncocin and apidaecin derivatives on key cells of the innate murine immune system suggests that their potent in vivo antibacterial activity relies on a direct antibacterial effect. This will simplify further pharmaceutical investigation and development of insect peptides as therapeutic compounds against bacterial infections. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

11.
    
Two simple lipid A analogues methyl 2,3-di-O-tetradecanoyl-alpha-D-glucopyranoside (GL1) and methyl 2,3-di-O-tetradecanoyl-alpha-D-glucopyranoside 4-O-phosphate (GL2) were synthesized and used for preparing mixed phosphocholine vesicles as models of the outer membrane of gram-negative bacteria. The interaction of these model membranes with magainin 2, a representative of the alpha-helical membrane active peptides, and apidaecin Ib and drosocin, two insect Pro-rich peptides which do not act at the level of the cellular membrane, were studied by CD and dye-releasing experiments. The CD spectra of apidaecin Ib and drosocin in the presence of GL1- or GL2-containing vesicles were consistent with largely unordered structures, whereas, according to the CD spectra, magainin 2 adopted an amphipathic alpha-helical conformation, particularly in the presence of negatively charged bilayers. The ability of the peptides to fold into amphipathic conformations was strictly correlated to their ability to bind and to permeabilize phospholipid as well as glycolipid membranes. Apidaecin Ib and drosocin, which are unable to adopt an amphipathic structure, showed negligible dye-leakage activity even in the presence of GL2-containing vesicles. It is reasonable to suppose that, as for the killing mechanism, the two classes of antimicrobial peptides follow different patterns to cross the bacterial outer membrane.  相似文献   

12.
    
Textilinin‐1 (Txln‐1), a Kunitz‐type serine protease inhibitor, is a 59‐amino‐acid polypeptide isolated from the venom of the Australian Common Brown snake Pseudonaja textilis textilis. This molecule has been suggested as an alternative to aprotinin, also a Kunitz‐type serine protease inhibitor, for use as an anti‐bleeding agent in surgical procedures. Txln‐1 shares only 47% amino‐acid identity to aprotinin; however, six cysteine residues in the two peptides are in conserved locations. It is therefore expected that the overall fold of these molecules is similar but that they have contrasting surface features. Here, the crystallization of recombinant textilinin‐1 (rTxln‐1) as the free molecule and in complex with bovine trypsin (229 amino acids) is reported. Two organic solvents, phenol and 1,4‐butanediol, were used as additives to facilitate the crystallization of free rTxln‐1. Crystals of the rTxln‐1–bovine trypsin complex diffracted to 2.0 Å resolution, while crystals of free rTxln‐1 diffracted to 1.63 Å resolution.  相似文献   

13.
    
Human Dickkopf‐1 (huDKK1), an inhibitor of the canonical Wnt‐signaling pathway that has been implicated in bone metabolism and other diseases, was expressed in engineered Chinese hamster ovary cells and purified. HuDKK1 is biologically active in a TCF/lef‐luciferase reporter gene assay and is able to bind LRP6 coreceptor. In SDS‐PAGE, huDKK1 exhibits molecular weights of 27–28 K and 30 K at ～ 1:9 ratio. By MALDI‐MS analysis, the observed molecular weights of 27.4K and 29.5K indicate that the low molecular weight form may contain O‐linked glycans while the high molecular weight form contains both N‐ and O‐linked glycans. LC‐MS/MS peptide mapping indicates that ～ 92% of huDKK1 is glycosylated at Asn225 with three N‐linked glycans composed of two biantennary forms with 1 and 2 sialic acid (23% and 60%, respectively), and one triantennary structure with 2 sialic acids (9%). HuDKK1 contains two O‐linked glycans, GalNAc (sialic acid)‐Gal‐sialic acid (65%) and GalNAc‐Gal[sialic acid] (30%), attached at Ser 30 as confirmed by β‐elimination and targeted LC‐MS/MS. The 10 intramolecular disulfide bonds at the N‐ and C‐terminal cysteine‐rich domains were elucidated by analyses including multiple proteolytic digestions, isolation and characterization of disulfide‐containing peptides, and secondary digestion and characterization of selected disulfide‐containing peptides. The five disulfide bonds within the huDKK1 N‐terminal domain are unique to the DKK family proteins; there are no exact matches in disulfide positioning when compared to other known disulfide clusters. The five disulfide bonds assigned in the C‐terminal domain show the expected homology with those found in colipase and other reported disulfide clusters.  相似文献   

14.
    
Pain is a major symptom of many diseases and results in enormous pressures on human body or society. Currently, clinically used analgesic drugs, including opioids and nonsteroidal anti‐inflammatory drugs, have adverse reactions, and thus, the development of new types of analgesic drug candidates is urgently needed. Animal venom peptides have proven to have potential as new types of analgesic medicine. In this research, we describe the isolation and characterization of an analgesic peptide from the crude venom of centipede, Scolopendra subspinipes mutilans. The amino acid sequence of this peptide was identical with SsmTX‐I that was previously reported as a specific Kv2.1 ion channel blocker. Our results revealed that SsmTX‐I was produced by posttranslational processing of a 73‐residue prepropeptide. The intramolecular disulfide bridge motifs of SsmTX‐I was Cys1–Cys3 and Cys2–Cys4. Functional assay revealed that SsmTX‐I showed potential analgesic activities in formalin‐induced paw licking, thermal pain, and acetic acid‐induced abdominal writhing mice models. Our research provides the first report of cDNA sequences, disulfide motif, successful synthesis, and analgesic potential of SsmTX‐I for the development of pain‐killing drugs. It indicates that centipede peptide toxins could be a treasure trove for the search of novel analgesic drug candidates. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

15.
    
The ants use their venom for predation, defense, and communication. The venom of these insects is rich in peptides and proteins, and compared with other animal venoms, ant venoms remain poorly explored. The objective of this study was to evaluate the protein content of the venom in the Ponerinae ant Pachycondyla striata. Venom samples were collected by manual gland reservoir dissection, and samples were submitted to two‐dimensional gel electrophoresis and separation by ion‐exchange and reverse‐phase high‐performance liquid chromatography followed by mass spectrometry using tanden matrix‐assisted laser desorption/ionization with time‐of‐flight (MALDI‐TOF/TOF) mass spectrometry and electrospray ionization‐quadrupole with time‐of‐flight (ESI‐Q/TOF) mass spectrometry for obtaining amino acid sequence. Spectra obtained were searched against the NCBInr and SwissProt database. Additional analysis was performed using PEAKS Studio 7.0 (Sequencing de novo). The venom of P. striata has a complex mixture of proteins from which 43 were identified. Within the identified proteins are classical venom proteins (phospholipase A, hyaluronidase, and aminopeptidase N), allergenic proteins (different venom allergens), and bioactive peptides (U10‐ctenitoxin Pn1a). Venom allergens are among the most expressed proteins, suggesting that P. striata venom has high allergenic potential. This study discusses the possible functions of the proteins identified in the venom of P. striata.  相似文献   

16.
    
Recent surveillance data on antimicrobial resistance predict the beginning of the post‐antibiotic era with pan‐resistant bacteria even overcoming polymyxin as the last available treatment option. Thus, new substances using novel modes of antimicrobial action are urgently needed to reduce this health threat. Antimicrobial peptides are part of the innate immune system of most vertebrates and invertebrates and accepted as valid substances for antibiotic drug development efforts. Especially, short proline‐rich antimicrobial peptides (PrAMP) of insect origin have been optimized for activity against Gram‐negative strains. They inhibit protein expression in bacteria by blocking the 70S ribosome exit tunnel (oncocin‐type) or the assembly of the 50S subunit (apidaecin‐type binding). Thus, apidaecin analog Api137 and oncocin analog Onc112 supposedly bind to different nearby or possibly partially overlapping binding sites. Here, we synthesized Api137/Onc112‐conjugates bridged by ethylene glycol spacers of different length to probe synergistic activities and binding modes. Indeed, the antimicrobial activities against Escherichia coli and Pseudomonas aeruginosa improved for some constructs, although the conjugates did not bind better to the 70S ribosome of E. coli than Api137 and Onc112 using 5(6)‐carboxyfluorescein‐labelled Api137 and Onc112 in a competitive fluorescence polarization assay. In conclusion, Api137/Onc112‐conjugates showed increased antimicrobial activities against P. aeruginosa and PrAMP‐susceptible and ‐resistant E. coli most likely because of improved membrane interactions, whereas the interaction to the 70S ribosome was most likely not improved relying still on the independent apidaecin‐ and oncocin‐type binding modes. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

17.
    
The structural effects of a representative “disallowed” conformation of Aib on the 310‐helical fold of an octapeptidomimetic are explored. The 1D (1H, 13C) & 2D NMR, FT‐IR and CD data reveal that the octapeptide 1 , adopts a 310‐helical conformation in solution, as it does in its crystal structure. The C‐terminal methyl carboxylate (CO2Me) of 1 was modified into an 1,3‐oxazine (Oxa) functional group in the peptidomimetic 2 . This modification results in the stabilization of the backbone of the C‐terminal Aib (Aib*‐Oxa) of 2 , in a conformation (ϕ, ψ = 180, 0) that is natively disallowed to Aib. Consequent to the presence of this natively disallowed conformation, the 310‐helical fold is not disrupted in the body of the peptidomimetic 2 . But the structural distortions that do occur in 2 are primarily in residues in the immediate vicinity of the natively disallowed conformation, rather than in the whole peptide body. Non‐native electronic effects resulting from modifications in backbone functional groups can be at the origin of stabilizing residues in natively disallowed conformations. © 2014 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 104: 21–36, 2015.  相似文献   

18.
    
Crotamine is defensin‐like cationic peptide from rattlesnake venom that possesses anticancer, antimicrobial, and antifungal properties. Despite these promising biological activities, toxicity is a major concern associated with the development of venom‐derived peptides as therapeutic agents. In the present study, we used zebrafish as a system model to evaluate the toxicity of rhodamine B‐conjugated (RhoB) crotamine derivative. The lethal toxic concentration of RhoB‐crotamine was as low as 4 μM, which effectively kill zebrafish larvae in less than 10 min. With non‐lethal concentrations (<1 μM), crotamine caused malformation in zebrafish embryos, delayed or completely halted hatching, adversely affected embryonic developmental programming, decreased the cardiac functions, and attenuated the swimming distance of zebrafish. The RhoB‐crotamine translocated across vitelline membrane and accumulated in zebrafish yolk sac. These results demonstrate the sensitive responsivity of zebrafish to trial crotamine analogues for the development of novel therapeutic peptides with improved safety, bioavailability, and efficacy profiles.  相似文献   

19.
    
A 1905-Da cationic proline-rich peptide, named SP-B, was recently isolated by our group as the main component of salivary gland granules, and its primary sequence fully characterized by means of automated Edman sequencing and LC-MS/MS tools. In the present study SP-B is shown to possess antifungal activity when challenged with strains of Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus, while only negligible antibacterial activity was detected. Furthermore, SP-B was found to be non-cytotoxic when tested on fibroblast cell lines. To obtain information regarding its structure affinity, capillary electrophoresis (CE), circular dichroism (CD) and attenuated total reflection (ATR)-FT/IR experiments were performed. CE revealed a pH dependence of the hydrodynamic radial dimensions both in aqueous and 2,2,2-trifluoroethanol solutions. CD and ATR-FT/IR measurements confirmed the structure-pH relationship, revealing a secondary structure composed of mixed proportions of polyproline-II, unordered and turn motifs, the last being more evident in the zwitterionic form of the peptide. From these findings SP-B peptide could be classified as a new member of the proline-rich antimicrobial peptide family.  相似文献   

20.
    
Nuclear magnetic resonance spectra of membrane proteins containing multiple transmembrane helices have proven difficult to resolve due to the redundancy of aliphatic and Ser/Thr residues in transmembrane domains and the low chemical shift dispersity exhibited by residues in α‐helical structures. Although 13C‐ and 15N‐labeling are useful tools in the biophysical analysis of proteins, selective labeling of individual amino acids has been used to help elucidate more complete structures and to probe ligand–protein interactions. In general, selective labeling has been performed in Escherichia coli expression systems using minimal media supplemented with a single labeled amino acid and nineteen other unlabeled amino acids and/or by using auxotrophs for specific amino acids. Growth in minimal media often results in low yields of cells or expression products. We demonstrate a method in which one labeled amino acid is added to a rich medium. These conditions resulted in high expression (≥100 mg/L) of a test fusion protein and milligram quantities of the selectively labeled membrane peptide after cyanogen bromide cleavage to release the peptide from the fusion protein. High levels of 15N incorporation and acceptable levels of cross‐labeling into other amino acid residues of the peptide were achieved. Growth in rich media is a simple and convenient alternative to growth in supplemented minimal media and is readily applicable to the expression of proteins selectively labeled with specific amino acids. © 2006 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 84: 508–518, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com  相似文献   

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