| 26930961 |
[Identification of ustiloxins in false smut balls of rice based on high performance liquid chromatography-high resolution mass spectrometry] |
10.3724/sp.j.1123.2015.04039. |
Se Pu |
[Identification of ustiloxins in false smut balls of rice based on high performance liquid chromatography-high resolution mass spectrometry]
Abstract
- A sensitive method was developed for the simultaneous identification of five ustiloxins in the false smut balls of rice by high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (HPLC-LTQ/Orbitrap MS). The samples were extracted with deionized water under ultrasonic condition for 10 min, then purified by a strong cation exchange column (PCX). The ustiloxins were separated on an Xselect HSS T3 column (150 mm x 2.1 mm, 3.5 μm) by using 0.1% (v/v) formic acid water solution and methanol as mobile phases with gradient elution at a flow rate of 0.3 mL/min. The full scan range was m/z 200-1 000. The confirmatory analysis of the target compounds was carried out by the accurate mass of quasi-molecular ion, isotope abundance ratio and qualitative fragments. The results showed that the five ustiloxins (A, B, C, D and F) were identified from the false smut balls with mass accuracy less than 1 x 10(-6) (1 ppm) and the absolute values of the deviation of isotope abundance ratio were not more than 3.3%. The product ions were consistent with the theoretical fragment mode. The recoveries were 90% to 105%. This method is accurate and sensitive for the simultaneous identification of the five ustiloxins, which can provide technical means for the research of the ability in toxin producing by Ustilaginodea virens.
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| 26965458 |
A high-throughput peptidomic strategy to decipher the molecular diversity of cyclic cysteine-rich peptides |
10.1038/srep23005. |
Sci Rep |
A high-throughput peptidomic strategy to decipher the molecular diversity of cyclic cysteine-rich peptides
Abstract
- Cyclotides are plant cyclic cysteine-rich peptides (CRPs). The cyclic nature is reported to be gene-determined with a precursor containing a cyclization-competent domain which contains an essential C-terminal Asn/Asp (Asx) processing signal recognized by a cyclase. Linear forms of cyclotides are rare and are likely uncyclizable because they lack this essential C-terminal Asx signal (uncyclotide). Here we show that in the cyclotide-producing plant Clitoria ternatea, both cyclic and acyclic products, collectively named cliotides, can be bioprocessed from the same cyclization-competent precursor. Using an improved peptidomic strategy coupled with the novel Asx-specific endopeptidase butelase 2 to linearize cliotides at a biosynthetic ligation site for transcriptomic analysis, we characterized 272 cliotides derived from 38 genes. Several types of post-translational modifications of the processed cyclotides were observed, including deamidation, oxidation, hydroxylation, dehydration, glycosylation, methylation, and truncation. Taken together, our results suggest that cyclotide biosynthesis involves 'fuzzy' processing of precursors into both cyclic and linear forms as well as post-translational modifications to achieve molecular diversity, which is a commonly found trait of natural product biosynthesis.
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| 27007913 |
Immunostimulating and Gram-negative-specific antibacterial cyclotides from the butterfly pea (Clitoria ternatea) |
10.1111/febs.13720. |
FEBS J |
Immunostimulating and Gram-negative-specific antibacterial cyclotides from the butterfly pea (Clitoria ternatea)
Abstract
- Cyclotides are plant-derived, cyclic miniproteins with three interlocking disulfide bonds that have attracted great interests because of their excellent stability and potential as peptide therapeutics. In this study, we characterize the cyclotides of the medicinal plant Clitoria ternatea (butterfly pea) and investigate their biological activities. Using a combined proteomic and transcriptomic method, we identified 41 novel cyclotide sequences, which we named cliotides, making C. ternatea one of the richest cyclotide-producing plants to date. Selected members of the cationic cliotides display potent antibacterial activity specifically against Gram-negative bacteria with minimal inhibitory concentrations as low as 0.5 μm. Remarkably, they also possess prominent immunostimulating activity. At a concentration of 1 μm, cationic cliotides are capable of augmenting the secretion of various cytokines and chemokines in human monocytes at both resting and lipopolysaccharide-stimulated states. Chemokines such as macrophage inflammatory proteins 1α and 1β, interferon γ-induced protein 10, interleukin 8 and tumor necrosis factor α were among the most upregulated with up to 129-fold increase in secretion level. These findings suggest cyclotides can serve as potential candidates for novel immunomodulating therapeutics.
The protein sequences reported in this paper (cT13-cT21) are available in the UniProt Knowledgebase under the accession numbers C0HJS0, C0HJS1, C0HJS2, C0HJS3, C0HJS4, C0HJS5, C0HJS6, C0HJS7 and C0HJS8, respectively. The transcriptome data in this paper are available at the Sequence Read Archive database (NCBI) under accession number SRR1613316. The protein precursors reported in this paper (ctc13, ctc15, ctc17-ctc19, ctc21-ctc53) are available at GenBank under the accession numbers KT732712, KT732713, KT732714, KT732715, KT732716, KT732717, KT732718, KT732719, KT732720, KT732721, KT732722, KT732723, KT732724, KT732725, KT732726, KT732727, KT732728, KT732729, KT732730, KT732731, KT732732, KT732733, KT732734, KT732735, KT732736, KT732737, KT732738, KT732739, KT732740, KT732741, KT732742, KT732743, KT732744, KT732745, KT732746, KT732747, KT732748 and KT732749, respectively.
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| 27026701 |
Development of a μO-Conotoxin Analogue with Improved Lipid Membrane Interactions and Potency for the Analgesic Sodium Channel NaV1.8 |
10.1074/jbc.M116.721662. |
J Biol Chem |
Development of a μO-Conotoxin Analogue with Improved Lipid Membrane Interactions and Potency for the Analgesic Sodium Channel NaV1.8
Abstract
- The μO-conotoxins MrVIA, MrVIB, and MfVIA inhibit the voltage-gated sodium channel NaV1.8, a well described target for the treatment of pain; however, little is known about the residues or structural elements that define this activity. In this study, we determined the three-dimensional structure of MfVIA, examined its membrane binding properties, performed alanine-scanning mutagenesis, and identified residues important for its activity at human NaV1.8. A second round of mutations resulted in (E5K,E8K)MfVIA, a double mutant with greater positive surface charge and greater affinity for lipid membranes compared with MfVIA. This analogue had increased potency at NaV1.8 and was analgesic in the mouse formalin assay.
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| 27035952 |
Oral activity of a nature-derived cyclic peptide for the treatment of multiple sclerosis |
10.1073/pnas.1519960113. |
Proc Natl Acad Sci U S A |
Oral activity of a nature-derived cyclic peptide for the treatment of multiple sclerosis
Abstract
- Multiple sclerosis (MS) is the most common autoimmune disease affecting the central nervous system. It is characterized by auto-reactive T cells that induce demyelination and neuronal degradation. Treatment options are still limited and several MS medications need to be administered by parenteral application but are modestly effective. Oral active drugs such as fingolimod have been weighed down by safety concerns. Consequently, there is a demand for novel, especially orally active therapeutics. Nature offers an abundance of compounds for drug discovery. Recently, the circular plant peptide kalata B1 was shown to silence T-cell proliferation in vitro in an IL-2-dependent mechanism. Owing to this promising effect, we aimed to determine in vivo activity of the cyclotide [T20K]kalata B1 using the MS mouse model experimental autoimmune encephalomyelitis (EAE). Treatment of mice with the cyclotide resulted in a significant delay and diminished symptoms of EAE by oral administration. Cyclotide application substantially impeded disease progression and did not exhibit adverse effects. Inhibition of lymphocyte proliferation and the reduction of proinflammatory cytokines, in particular IL-2, distinguish the cyclotide from other marketed drugs. Considering their stable structural topology and oral activity, cyclotides are candidates as peptide therapeutics for pharmaceutical drug development for treatment of T-cell-mediated disorders.
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| 27063928 |
Safety, tolerability, pharmacokinetics and pharmacodynamics of AZP-531, a first-in-class analogue of unacylated ghrelin, in healthy and overweight/obese subjects and subjects with type 2 diabetes |
10.1111/dom.12675. |
Diabetes Obes Metab |
Safety, tolerability, pharmacokinetics and pharmacodynamics of AZP-531, a first-in-class analogue of unacylated ghrelin, in healthy and overweight/obese subjects and subjects with type 2 diabetes
Abstract
- To explore the safety, pharmacokinetics and pharmacodynamics in humans of the unacylated ghrelin analogue AZP-531, designed to improve glycaemic control and reduce weight.
Assessments, including glucose measurements, were performed in a three-part randomized study. In Part A, healthy subjects [n = 44, age 18-50 years, body mass index (BMI) 20-28 kg/m(2) ] received a single subcutaneous dose of 0.3, 3, 15, 30, 60 or 120 µg/kg AZP-531 or placebo. In Part B, overweight/obese subjects (n = 32, age 18-65 years, BMI 28-38 kg/m(2) ) and in Part C, patients with type 2 diabetes [T2D; n = 36, age 18-65 years, BMI 20-40 kg/m(2) , glycated haemoglobin (HbA1c) 7-10%] received AZP-531 or placebo for 14 days (daily doses of 3, 15, 30 or 60 µg/kg and 15, 2 × 30 or 60 µg/kg, respectively).
AZP-531 was well tolerated. Single- and multiple-dose pharmokinetic variables were similar. Maximum AZP-531 concentrations were typically reached at 1 h post-dose. Observed maximum concentration (Cmax ) and area under the curve were dose-proportional. The mean terminal half-life (t1/2 ) was 2-3 h. In Part B, AZP-531 doses of ≥15 µg/kg significantly improved glucose concentrations, without increasing insulin levels, suggesting an insulin-sensitizing effect. AZP-531 decreased mean body weight by 2.6 kg (vs 0.8 kg for placebo). In Part C, glucose variables improved in all groups, including placebo, suggesting a study effect in uncontrolled patients at baseline. Notwithstanding, AZP-531 60 µg/kg reduced HbA1c by 0.4% (vs 0.2% for placebo) and body weight by 2.1 kg (vs 1.3 kg for placebo).
AZP-531 was well tolerated in this first-in-human study. Its pharmacokinetic profile, suitable for once-daily dosing, and metabolic effects support further clinical development for T2D.
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| 27082849 |
[1-8-NαC]-Zanriorb A1, a Proapoptotic Orbitide from Leaves of Zanthoxylum riedelianum |
10.1021/acs.jnatprod.5b00177. |
J Nat Prod |
[1-8-NαC]-Zanriorb A1, a Proapoptotic Orbitide from Leaves of Zanthoxylum riedelianum
Abstract
- A new orbitide named [1-8-NαC]-zanriorb A1 (1) was isolated and characterized from the leaves of Zanthoxylum riedelianum using NMR and mass spectrometry. The absolute configuration of the amino acids was determined using Marfey's method on the acid hydrolysates. Compound 1 induced cell death by apoptosis in Jurkat leukemia T cells (IC50 218 nM).
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| 27093300 |
Efficient enzymatic cyclization of an inhibitory cystine knot-containing peptide |
10.1002/bit.25993. |
Biotechnol Bioeng |
Efficient enzymatic cyclization of an inhibitory cystine knot-containing peptide
Abstract
- Disulfide-rich peptides isolated from cone snails are of great interest as drug leads due to their high specificity and potency toward therapeutically relevant ion channels and receptors. They commonly contain the inhibitor cystine knot (ICK) motif comprising three disulfide bonds forming a knotted core. Here we report the successful enzymatic backbone cyclization of an ICK-containing peptide κ-PVIIA, a 27-amino acid conopeptide from Conus purpurascens, using a mutated version of the bacterial transpeptidase, sortase A. Although a slight loss of activity was observed compared to native κ-PVIIA, cyclic κ-PVIIA is a functional peptide that inhibits the Shaker voltage-gated potassium (Kv) channel. Molecular modeling suggests that the decrease in potency may be related to the loss of crucial, but previously unidentified electrostatic interactions between the N-terminus of the peptide and the Shaker channel. This hypothesis was confirmed by testing an N-terminally acetylated κ-PVIIA, which shows a similar decrease in activity. We also investigated the conformational dynamics and hydrogen bond network of cyc-PVIIA, both of which are important factors to be considered for successful cyclization of peptides. We found that cyc-PVIIA has the same conformational dynamics, but different hydrogen bond network compared to those of κ-PVIIA. The ability to efficiently cyclize ICK peptides using sortase A will enable future protein engineering for this class of peptides and may help in the development of novel therapeutic molecules. Biotechnol. Bioeng. 2016;113: 2202-2212. © 2016 Wiley Periodicals, Inc.
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| 27097793 |
Proline cis-trans isomerization and its implications for the dimerization of analogues of cyclopeptide stylostatin 1: a combined computational and experimental study |
10.1039/c5cp05937b. |
Phys Chem Chem Phys |
Proline cis-trans isomerization and its implications for the dimerization of analogues of cyclopeptide stylostatin 1: a combined computational and experimental study
Abstract
- Cis and trans proline conformers are often associated with dramatic changes in the biological function of peptides. A slow equilibrium between cis and trans Ile-Pro amide bond conformers occurs in constrained derivatives of the native marine cyclic heptapeptide stylostatin 1 (cyclo-(NSLAIPF)), a potential anticancer agent. In this work, four cyclopeptides, cyclo-(NSTAIPF), cyclo-(KSTAIPF), cyclo-(RSTAIPF) and cyclo-(DSTAIPF), which are structurally related to stylostatin 1, are experimentally and computationally examined in order to assess the effect of residue mutations on the cis-trans conformational ratio and the apparent capacity to form dimeric aggregates. Primarily, cyclo-(KSTAIPF) and cyclo-(RSTAIPF) showed specific trends in circular dichroism, MALDI-TOF and HPLC purification experiments, which suggests the occurrence of peptide dimerization. Meanwhile, the NMR spectrum of cyclo-(KSTAIPF) indicates that this cyclopeptide exists in the two slow-exchange families of conformations mentioned above. Molecular dynamics simulations combined with quantum mechanical calculations have shed light on the factors governing the cis/trans conformational ratio. In particular, we have found that residue mutations affect the internal hydrogen bond pattern which ultimately tunes the cis/trans conformational ratio and that only trans conformers are capable of aggregating due to the shape complementarity of the two subunits.
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| 27105996 |
Potential of mZD7349-conjugated PLGA nanoparticles for selective targeting of vascular cell-adhesion molecule-1 in inflamed endothelium |
10.1016/j.mvr.2016.04.003. |
Microvasc Res |
Potential of mZD7349-conjugated PLGA nanoparticles for selective targeting of vascular cell-adhesion molecule-1 in inflamed endothelium
Abstract
- Early diagnosis and restoring normal function of dysfunctional endothelium is an attractive strategy for prevention of inflammatory diseases such as atherosclerosis. Inhibition of cell adhesion in the process of atherosclerosis plaque formation, mediated by peptide antagonists of very late antigen-4 (VLA-4) has already been developed and evaluated both in vitro and in vivo. In this study, for the first time, modified ZD7349 (mZD7349) peptide, as an antagonist for VLA-4, was used for targeting fluorescein isothiocyanate-loaded poly (DL-lactic-co-glycolic acid) nanoparticles (FITC-PLGA NPs). Rate of binding and internalization of mZD7349-NPs to activated human umbilical vein endothelial cells (HUVECs) were compared with that of untargeted. Effects of temperature reduction and clathrin-mediated endocytosis inhibitor (0.45M sucrose) were also studied on the binding and internalization of mZD7349-NPs and NPs. Results showed that binding of the conjugated NPs could be significantly blocked by pre-incubating cells with the free peptide, suggesting that the binding of NPs is mediated by attaching the surface peptide to VCAM-1 on HUVECs. Also, conjugated FITC-loaded NPs were shown to be rapidly endocytosized to a greater extent than the unconjugated ones. The binding and internalization of mZD7349-NPs and NPs were slowed down at low temperature and in the presence of sucrose with greater reductions for mZD7349-NPs. To conclude, the peptide-NPs targeting the VCAM-1 is suggested as a theranostic carrier for lesions upregulating VCAM-1.
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| 27114317 |
Two novel antimicrobial peptides from skin venoms of spadefoot toad Megophrys minor |
10.1016/S1875-5364(16)30030-9. |
Chin J Nat Med |
Two novel antimicrobial peptides from skin venoms of spadefoot toad Megophrys minor
Abstract
- Amphibian skin contains rich bioactive peptides. Especially, a large amount of antimicrobial peptides have been identified from amphibian skin secretions. Antimicrobial peptides display potent cytolytic activities against a range of pathogenic bacteria and fungi and play important defense roles. No antimicrobial peptides have been reported from toads belonging to the family of Pelobatidae. In this work, two novel antimicrobial peptides (Megin 1 and Megin 2) were purified and characterized from the skin venoms of spadefoot toad Megophrys minor (Pelobatidae, Anura, Amphibia). Megin 1 had an amino acid sequence of FLKGCWTKWYSLKPKCPF-NH2, which was composed of 18 amino acid residues and contained an intra-molecular disulfide bridge and an amidated C-terminus. Megin 2 had an amino acid sequence of FFVLKFLLKWAGKVGLEHLACKFKNWC, which was composed of 27 amino acid residues and contained an intra-molecular disulfide bridge. Both Megin 1 and Megin 2 showed potential antimicrobial abilities against bacteria and fungi. The MICs of Megin 1 against Escherichia coli, Bacillus dysenteriae, Staphylococcus aureus, Bacillus subtilis, and Candida albicans were 25, 3, 6.25, 3, and 50 μg·mL(-1), respectively. The corresponding MICs for Megin 2 were 6.25, 1.5, 12.5, 1.5, and 12.5 μg·mL(-1), respectively. They also exerted strong hemolytic activity against human and rabbit red cells. The results suggested that megin peptides in the toad skin of M. minor displayed toxic effects on both eukaryotes and prokaryotes. This was the first report of antimicrobial peptides from amphibians belonging to the family of Pelobatidae.
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| 27115623 |
Occurrence of microcystins in water, bloom, sediment and fish from a public water supply |
10.1016/j.scitotenv.2016.04.027. |
Sci Total Environ |
Occurrence of microcystins in water, bloom, sediment and fish from a public water supply
Abstract
- Microcystin (MC) accumulation was determined in the liver and muscle of two omnivorous fish species which are consumed and are economically important, and in a planktivorous-carnivorous fish from Lake Eğirdir, Turkey. Free extractable MCs in fish tissue samples were detected by enzyme-linked immunosorbent assay (ELISA) with confirmation by high performance liquid chromatography with photodiode array detection (HPLC-PDA). MC-LA and -YR, were detected in both liver and muscle, followed by MCs -LY, -LF, -RR and -LR respectively. The MC concentrations varied between 0.043 and 1.72μg/g dry weight in liver and muscle tissues. MCs were also determined in samples of water, sediment and a bloom sample of Microcystis aeruginosa from the lake by HPLC-PDA. MC-LY and -YR were most commonly identified in water samples, with total MC concentrations ranging from 2.9±0.05 to 13.5±2.3μg/L. Sediment analyses, showed that MC-YR was present in samples between 7.0 and 17.6μg/g dw, especially in October, November and December when no MC-YR was recorded in water, followed by MC-LW. The findings indicate that water and sediment contained MCs, and more importantly that fish were contaminated with MCs that may pose an MC-associated human health risk.
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| 27166860 |
Unveiling the Biosynthetic Pathway of the Ribosomally Synthesized and Post-translationally Modified Peptide Ustiloxin B in Filamentous Fungi |
10.1002/anie.201602611. |
Angew Chem Int Ed Engl |
Unveiling the Biosynthetic Pathway of the Ribosomally Synthesized and Post-translationally Modified Peptide Ustiloxin B in Filamentous Fungi
Abstract
- The biosynthetic machinery of the first fungal ribosomally synthesized and post-translationally modified peptide (RiPP) ustiloxin B was elucidated through a series of gene inactivation and heterologous expression studies. The results confirmed an essential requirement for novel oxidases possessing the DUF3328 motif for macrocyclization, and highly unique side-chain modifications by three oxidases (UstCF1F2) and a pyridoxal 5'-phosphate (PLP)-dependent enzyme (UstD). These findings provide new insight into the expression of the RiPP gene clusters found in various fungi.
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| 27322468 |
Targeting the PDGF-B/PDGFR-β Interface with Destruxin A5 to Selectively Block PDGF-BB/PDGFR-ββ Signaling and Attenuate Liver Fibrosis |
10.1016/j.ebiom.2016.03.042. |
EBioMedicine |
Targeting the PDGF-B/PDGFR-β Interface with Destruxin A5 to Selectively Block PDGF-BB/PDGFR-ββ Signaling and Attenuate Liver Fibrosis
Abstract
- PDGF-BB/PDGFR-ββ signaling plays very crucial roles in the process of many diseases such as liver fibrosis. However, drug candidates with selective affinities for PDGF-B/PDGFR-β remain deficient. Here, we identified a natural cyclopeptide termed destruxin A5 that effectively inhibits PDGF-BB-induced PDGFR-β signaling. Interestingly and importantly, the inhibitory mechanism is distinct from the mechanism of tyrosine kinase inhibitors because destruxin A5 does not have the ability to bind to the ATP-binding pocket of PDGFR-β. Using Biacore T200 technology, thermal shift technology, microscale thermophoresis technology and computational analysis, we confirmed that destruxin A5 selectively targets the PDGF-B/PDGFR-β interaction interface to block this signaling. Additionally, the inhibitory effect of destruxin A5 on PDGF-BB/PDGFR-ββ signaling was verified using in vitro, ex vivo and in vivo models, in which the extent of liver fibrosis was effectively alleviated by destruxin A5. In summary, destruxin A5 may represent an efficacious and more selective inhibitor of PDGF-BB/PDGFR-ββ signaling.
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| 27333558 |
Stereoselective Synthesis of Southern Fragment of Hantupeptin A |
10.17344/acsi.2016.2322. |
Acta Chim Slov |
Stereoselective Synthesis of Southern Fragment of Hantupeptin A
Abstract
- The stereoselective synthesis of the southern fragment (C21-C41) of Hantupeptin A is described. The required stereochemistry of β-hydroxy-α-methyl acid unit was accomplished through the Aldol reaction using Evan's chiral auxiliary followed by the installation of the terminal alkyne with Ohira-Bestmann reagent.
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