摘要:

Scolopendra subspinipes mutilans, also known as Chinese red‐headed centipede, is a venomous centipede from East Asia and Australasia. Venom from this animal has not been researched as thoroughly as venom from snakes, snails, scorpions, and spiders. In this study, we isolated and characterized SsmTx‐I, a novel neurotoxin from the venom ofS. subspinipes mutilans. SsmTx‐I contains 36 residues with four cysteines forming two disulfide bonds. It had low sequence similarity (<10%) with other identified peptide toxins. By whole‐cell recording, SsmTx‐I significantly blocked voltage‐gated K+channels in dorsal root ganglion neurons with an IC50value of 200 nM, but it had no effect on voltage‐gated Na+channels. Among the nine K+channel subtypes expressed in human embryonic kidney 293 cells, SsmTx‐I selectively blocked the Kv2.1 current with an IC50value of 41.7 nM, but it had little effect on currents mediated by other K+channel subtypes. Blockage of Kv2.1 by SsmTx‐I was not associated with significant alteration of steady‐state activation, suggesting that SsmTx‐I might act as a simple inhibitor or channel blocker rather than a gating modifier. Our study reported a specific Kv2.1‐blocker from centipede venom and provided a basis for future investigations of SsmTx‐I, for example on structure–function relationships, mechanism of action, and pharmacological potential. Copyright © 2014 European Peptid

ISSN:1075-2617    

DOI:10.1002/psc.2588

年代:2014

数据来源: WILEY

摘要:

Slc11a1 is an integral membrane protein with 12 putative transmembrane domains and functions as a pH‐coupled divalent metal cation transporter. In the present study, the structures of the peptides corresponding to the second and fifth transmembrane domains of Slc11a1 (from 88 to 109 for TMD2 and from 190 to 215 for TMD5) were determined in membrane‐mimic environments by CD and NMR techniques. It was demonstrated that TMD2 and TMD5 form anα‐helical structure in 30% 2,2,2‐trifluoroethanol (TFE) and 40% hexafluoro‐2‐propanol (HFIP) aqueous solution, respectively. Theα‐helix of TMD5 displays a less space‐occupied face consisting of the residues Ala194, Gly197, Thr201, Ala204 and Gly208. Theα‐helix is partially unfolded in theN‐terminal region when Gly197 is substituted by Val. The unfolding of the helix in theN‐terminal part and/or increase in volume at the less space‐occupied face of the helix may exert an effect on the arrangement of TMD5 in membrane. Copyright © 2014 European Peptide Socie

ISSN:1075-2617    

DOI:10.1002/psc.2593

年代:2014

数据来源: WILEY

摘要:

A new microbial cyclic dipeptide (diketopiperazine), cyclo(d‐Tyr‐d‐Phe) was isolated for the first time from the ethyl acetate extract of fermented modified nutrient broth ofBacillussp. N strain associated with rhabditid Entomopathogenic nematode. Antibacterial activity of the compound was determined by minimum inhibitory concentration and agar disc diffusion method against medically important bacteria and the compound recorded significant antibacterial against test bacteria. Highest activity was recorded againstStaphylococcus epidermis(1 µg/ml) followed byProteus mirabilis(2 µg/ml). The activity of cyclo(d‐Tyr‐d‐Phe) againstS.epidermisis better than chloramphenicol, the standard antibiotics. Cyclo(d‐Tyr‐d‐Phe) recorded significant antitumor activity against A549 cells (IC50value: 10 μM) and this compound recorded no cytotoxicity against factor signaling normal fibroblast cells up to 100 μM. Cyclo(d‐Tyr‐d‐Phe) induced significant morphological changes and DNA fragmentation associated with apoptosis in A549 cells. Acridine orange/ethidium bromide stained cells indicated apoptosis induction by cyclo(d‐Tyr‐d‐Phe). Flow cytometry analysis showed that the cyclo(d‐Tyr‐d‐Phe) did not induce cell cycle arrest. Effector molecule of apoptosis such as caspase‐3 was found activated in treated cells, suggesting apoptosis as the main mode of cell death. Antioxidant activity was evaluated by free radical scavenging and reducing power activity, and the compound recorded significant antioxidant activity. The free radical scavenging activity of cyclo(d‐Tyr‐d‐Phe) is almost equal to that of butylated hydroxyanisole, the standard antioxidant agent. We also compared the biological activity of natural cyclo(d‐Tyr‐d‐Phe) with synthetic cyclo(d‐Tyr‐d‐Phe) and cyclo(l‐Tyr‐l‐Phe). Natural and synthetic cyclo(d‐Tyr‐d‐Phe) recorded similar pattern of activity. Although synthetic cyclo(l‐Tyr‐l‐Phe) recorded lower activity. But in the case of reducing power activity, synthetic cyclo(l‐Tyr‐l‐Phe) recorded significant activity than natural and synthetic cyclo(d‐Tyr‐d‐Phe). The results of the present study reveals that cyclo(d‐Tyr‐d‐Phe) is more bioactive than cyclo(l‐Tyr‐l‐Phe). To the best of our knowledge, this is the first time that cyclo(d‐Tyr‐d‐Phe) has been isolated from microbial natural source and also the antibacterial, anticancer, and antioxidant activity of cyclo(d

ISSN:1075-2617    

DOI:10.1002/psc.2594

年代:2014

数据来源: WILEY

摘要:

A considerable quantity of an alkylation by‐product is observed when using 3,6‐dioxa‐1,8‐octanedithiol as a scavenger during acidic release of peptides containing the thioether amino acid methionine from the solid support. Adjustment of the cleavage conditions by replacement of 3,6‐dioxa‐1,8‐octanedithiol with ethane dithiol or by using methionine sulfoxide as an alternative to methionine resulted in no such impurity. The by‐product was detectable by liquid chromatography and mass spectrometry and characterised by NMR spectroscopy of an isolated model peptide. It could be effectively removed in a separate post cleavage step by treatment with dilute aqueous acid at 37 °C. Copyright © 2013 European Peptide Society and J

ISSN:1075-2617    

DOI:10.1002/psc.2595

年代:2014

数据来源: WILEY

摘要:

Use of the 4‐pyridylmethyl ester group for side‐chain protection of glutamic acid residues in solid‐phase peptide synthesis enables switching of the charge state of a peptide from negative to positive, thus making detection by positive ion mode ESI‐MS possible. The pyridylmethyl ester moiety is readily removed from peptides in high yield by hydrogenation. Combining the 4‐pyridylmethyl ester protecting group with benzyl ester protection reduces the number of the former needed to produce a net positive charge and allows for purification by RP HPLC. This protecting group is useful in the synthesis of highly acidic peptide sequences, which are often beset by problems with purification by standard RP HPLC and characterization by ESI‐MS. Copyright © 2014 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.2598

年代:2014

数据来源: WILEY

摘要:

To screen and identify the novel probe markers binding hepatocellular carcinoma specifically and sensitively, a phage‐displayed 12‐mer peptide library was used to make biopanning with the modified protocols on HepG2 cells. After four rounds of panning, the consensus sequences were obtained, and the PC28, a phage clone with most specific and sensitive binding to HepG2 cells, was identified as the best positive clone. The peptide probe HCSP4 (sequence SLDSTHTHAPWP) was synthesized based on the sequencing result of PC28. The specificity and sensitivity of HCSP4 were primarily analyzed using immunofluorescence, flow cytometry, and other methods. The results show that HCSP4 can bind to hepatocellular carcinoma cells with satisfactory specificity and sensitivity. It may be a promising lead candidate for molecular imaging and targeted drug delivery in the diagnosis and therapy of hepatocellular carcinoma. Copyright © 2014 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.2599

年代:2014

数据来源: WILEY

摘要:

The influence of aqueous environment on the main‐chain conformation (ω0, ϕ, and ψ dihedral angles) of two model peptoids:N‐acetyl‐N‐methylglycineN’‐methylamide (Ac‐N(Me)‐Gly‐NHMe) (1) andN‐acetyl‐N‐methylglycineN’,N’‐dimethylamide (Ac‐N(Me)‐Gly‐NMe2) (2) was investigated by MP2/6‐311++G(d,p) method. The Ramachandran maps of both studied molecules withcisandtransconfiguration of the N‐terminal amide bond in the gas phase and in water environment were obtained and all energy minima localized. The polarizable continuum model was applied to estimate the solvation effect on conformation. Energy minima of the Ac‐N(Me)‐Gly‐NHMe and Ac‐N(Me)‐Gly‐NMe2have been analyzed in terms of the possible hydrogen bonds and C = O dipole attraction. To validate the theoretical results obtained, conformations of the similar structures gathered in the Cambridge Crystallographic Data Centre were analyzed. Obtained results indicate that aqueous environment in model peptoids1and2favors the conformation F (ϕ and ψ = −70º, 180º), and additionally significantly increases the percentage of structures withcisconfiguration of N‐terminal amide bond in studied compoun

ISSN:1075-2617    

DOI:10.1002/psc.2601

年代:2014

数据来源: WILEY

摘要:

Synthetic peptide octarphin (TPLVTLFK, a selective agonist of nonopioidβ‐endorphin receptor) was able to activate in a dose‐dependent manner murine macrophages to express nitric oxide (NO) synthase and to produce NO. Octarphin required lipopolysacharide for the optimal induction of NO production. Octarphin‐dependent NO production was sensitive to inhibition by dexamethasone and the NO synthase specific inhibitor NG‐monomethyl‐l‐arginine. In the concentration range of 1–1000 nM, octarphin increased the cyclic 3′,5′‐guanosine monophosphate (cGMP) content in macrophages stimulated with lipopolysacharide. The effect was dependent on the peptide concentration and was maximal at a concentration of 100 nM. Thus, octarphin stimulates both NO and cGMP production in macrophages. Copyright © 2014 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.2603

年代:2014

数据来源: WILEY

摘要:

A procedure for obtaining isotopically labeled peptides, by combining affinity chromatography, urea‐equilibrated gel filtration, and hydrophobic chromatography procedures, is presented using the Disabled‐2 (Dab2) sulfatide‐binding motif (SBM) as a proof of concept. The protocol is designed to isolate unstructured, membrane‐binding, recombinant peptides that co‐purify with bacterial proteins (e.g., chaperones). Dab2 SBM is overexpressed in bacteria as an isotopically labeled glutathione S‐transferase (GST) fusion protein using minimal media containing [15N] ammonium chloride as the nitrogen source. The fusion protein is purified using glutathione beads, and Dab2 SBM is released from GST using a specific protease. It is then dried, resuspended in urea to release the bound bacterial protein, and subjected to urea‐equilibrated gel filtration. Urea and buffer reagents are removed using an octadecyl column. The peptide is eluted with acetonitrile, dried, and stored at −80 °C. Purification of Dab2 SBM can be accomplished in 6 days with a yield of ~2 mg/l of culture. The properties of Dab2 SBM can be studied in the presence of detergents using NMR spectroscopy. Although this method also allows for the purification of unlabeled peptides that co‐purify with bacterial proteins, the procedure is more relevant to isotopically labeled peptides, thus alleviating the cost of peptide production. Copyright © 2014 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.2604

年代:2014

数据来源: WILEY

摘要:

Self‐assembly of PAs composed of palmitic acid and several repeated heptad peptide sequences, C15H31CO‐(IEEYTKK)n‐NH2(n = 1–4, represented by PA1–PA4), was investigated systematically. The secondary structures of the PAs were characterized by CD. PA3 and PA4 (n = 3 and 4, respectively) showed anα‐helical structure, whereas PA1 and PA2 (n = 1 and 2, respectively) did not display anα‐helical conformations under the tested conditions. The morphology of the self‐assembled peptides in aqueous medium was studied by transmission electron microscopy. As the number of heptad repeats in the PAs increased, the nanostructure of the self‐assembled peptides changed from nanofibers to nanovesicles. Changes of the secondary structures and the self‐assembly morphologies of PA3 and PA4 in aqueous medium with various cations were also studied. The critical micelle concentrations were determined using a pyrene fluorescence probe. In conclusion, this method may be used to design new peptide nanomaterials. Copyright © 2014 European Peptid

ISSN:1075-2617    

DOI:10.1002/psc.2606

年代:2014

数据来源: WILEY