1.
Synthesis, evaluation and molecular modeling of cyclic tetrapeptide histone deacetylase inhibitors as anticancer agents.
Source
School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China.
Abstract
Histone deacetylase inhibitors (HDACIs) are a promising class of anticancer agents. To examine whether a slight change in the recognition domain could alter their inhibitory activity, we synthesized a series of cyclo(-l-Am7(S2Py)-Aib-l-Phe(n-Me)-d-Pro)derivatives and evaluated their HDAC inhibitory and anticancer activities. The peptides exhibited potent HDAC inhibitory activity and inhibited three human cancer cell lines with IC(50) in the micromolar range. Docking and molecular dynamics simulation were conducted to explore the interaction mechanisms of class I and II HDACs with these inhibitors. It revealed that the zinc ion in the active site coordinated five atoms of HDACs and the sulfur atom of the inhibitor. The metal binding domains of these compounds interacted with HDAC2, and the surface recognition domains of these compounds interacted with HDAC4 through hydrogen bonding. The hydrophobic interactions also provided favorable contributions to stabilize the complexes. The results obtained from this study would be helpful for us to design some novel cyclic tetrapeptides that may act as potent HDACIs. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
- PMID:
- 22253009
- [PubMed - as supplied by publisher]
Antimicrobial activity of peptides derived from human ß-amyloid precursor protein.
Source
Division of Dermatology and Venereology, Department of Clinical Sciences, Lund University, Biomedical Center, Tornavägen 10, SE-221 84, Lund, Sweden.
Abstract
Antimicrobial peptides are important effector molecules of the innate immune system. Here, we describe that peptidesderived from the heparin-binding disulfide-constrained loop region of human ß-amyloid precursor protein are antimicrobial. The peptides investigated were linear and cyclic forms of NWCKRGRKQCKTHPH (NWC15) as well as thecyclic form comprising the C-terminal hydrophobic amino acid extension FVIPY (NWCKRGRKQCKTHPHFVIPY; NWC20c). Compared with the benchmark antimicrobial peptide LL-37, these peptides efficiently killed the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, the Gram-positive Staphylococcus aureus and Bacillus subtilis, and the fungi Candida albicans and Candida parapsilosis. Correspondingly, fluorescence and electron microscopy demonstrated that the peptides caused defects in bacterial membranes. Analogously, the peptidespermeabilised negatively charged liposomes. Despite their bactericidal effect, the peptides displayed very limited hemolytic activities within the concentration range investigated and exerted very small membrane permeabilising effects on human epithelial cells. The efficiency of the peptides with respect to bacterial killing and liposome membrane leakage was in the order NWC20c > NWC15c > NWC15l, which also correlated to the adsorption density for these peptides at the model lipid membrane. Thus, whereas the cationic sequence is a minimum determinant for antimicrobial action, a constrained loop-structure as well as a hydrophobic extension further contributes to membrane permeabilising activity of this region of amyloid precursor protein. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
Analysis of YM-216391 Biosynthetic Gene Cluster and Improvement of the Cyclopeptide Production in Heterologous Host.
Abstract
YM-216391, an antitumor natural product, represents a new class of cyclic peptides containing a polyoxazole-thiazole moiety. Herein we describe its gene cluster encoding the biosynthetic paradigm featuring a ribosomally synthesizing precursor peptide followed by a series of novel posttranslational modifications, which include i) cleavage of both N-terminal leader peptide and C-terminal extension peptide and cyclization in a head-to-tail fashion, ii) conversion of an L-Ile to D-allo-Ile, and iii) -hydroxylation of Phe by a P450 monooxygenase followed by further heterocyclization and oxidation to form a phenyloxazole moiety. The cluster was heterologously expressed in Streptomyces lividans to bypass difficult genetic manipulation. Deletion of the ymR3 gene, encoding a putative transcriptional regulator, increased the YM-216391 yield about 20-fold higher than the original yields for the heterologous expression of wild-type cluster, which set the stage for further combinatorial biosynthesis.
cNGR conjugated poly(lactic acid)-poly(ethylene glycol) nanoparticles for targeted gene delivery.
Abstract
Cyclic asparagines-glycine-arginine (cNGR) peptide was used to target gene loaded poly(lactic acid)-poly(ethylene glycol) nanoparticles (PLA-PEG NPs) to human umbilical vein endothelial cells (HUVEC). cNGR modified gene loaded PLA-PEG nanoparticles (cNGR-PLA-PEG NPs) could effectively condense DNA into small-sized complexes (<200nm) with positive charge (~10mV) using a novel cationic surfactant, 6-lauroxyhexyl lysinate (LHLN). cNGR-PLA-PEG NPs could be internalized into HUVEC by caveolae-mediated endocytosis with higher gene transfection efficiency and lower cytotoxicity than PLA-PEG NPs.
Copyright © 2011. Published by Elsevier B.V.
A Cyclic Peptide Inhibitor of ApoC-II Peptide Fibril Formation: Mechanistic Insight from NMR and Molecular Dynamics Analysis.
Source
Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
Abstract
The misfolding and aggregation of proteins to form amyloid fibrils is a characteristic feature of several common age-related diseases. Agents that directly inhibit formation of amyloid fibrils represent one approach to combating these diseases. We have investigated the potential of a cyclic peptide to inhibit fibril formation by fibrillogenic peptides from human apolipoprotein C-II (apoC-II). Cyc[60-70] was formed by disulfide cross-linking of cysteine residues added to the termini of the fibrillogenic peptide comprising apoC-II residues 60-70. This cyclic peptide did not self-associate into fibrils. However, substoichiometric concentrations of cyc[60-70] significantly delayed fibril formation by the fibrillogenic, linear peptides apoC-II[60-70] and apoC-II[56-76]. Reduction of the disulfide bond or scrambling the amino acid sequence within cyc[60-70] significantly impaired its inhibitory activity. The solution structure of cyc[60-70] was solved using NMR spectroscopy, revealing a well-defined structure comprising a hydrophilic face and a more hydrophobic face containing the Met60, Tyr63, Ile66 and Phe67 side chains. Molecular dynamics (MD) studies identified a flexible central region within cyc[60-70], while MD simulations of "scrambled" cyc[60-70] indicated an increased formation of intramolecular hydrogen bonds and a reduction in the overall flexibility of the peptide. Our structural studies suggest that the inhibitory activity of cyc[60-70] is mediated by an elongated structure with inherent flexibility and distinct hydrophobic and hydrophilic faces, enabling cyc[60-70] to interact transiently with fibrillogenic peptides and inhibit fibril assembly. These results suggest that cyclic peptides based on amyloidogenic core peptides could be useful as specific inhibitors of amyloid fibril formation.
Copyright © 2011. Published by Elsevier Ltd.
Interleukin 15 levels in serum may predict a severe disease course in patients with early arthritis.
Source
Rheumatology Service, Hospital Universitario de La Princesa, IIS Princesa, Madrid, Spain.
Abstract
BACKGROUND:
Interleukin-15 (IL-15) is thought to be involved in the physiopathological mechanisms of RA and it can be detected in the serum and the synovial fluid of inflamed joints in patients with RA but not in patients with osteoarthritis or other inflammatory joint diseases. Therefore, the objective of this work is to analyse whether serum IL-15 (sIL-15) levels serve as a biomarker of disease severity in patients with early arthritis (EA).
METHODOLOGY AND RESULTS:
Data from 190 patients in an EA register were analysed (77.2% female; median age 53 years; 6-month median disease duration at entry). Clinical and treatment information was recorded systematically, especially the prescription of disease modifying anti-rheumatic drugs. Two multivariate longitudinal analyses were performed with different dependent variables: 1) DAS28 and 2) a variable reflecting intensive treatment. Both included sIL-15 as predictive variable and other variables associated with disease severity, including rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibodies (ACPA). Of the 171 patients (638 visits analysed) completing the follow-up, 71% suffered rheumatoid arthritis and 29% were considered as undifferentiated arthritis. Elevated sIL-15 was detected in 29% of this population and this biomarker did not overlap extensively with RF or ACPA. High sIL-15 levels (β Coefficient [95% confidence interval]: 0.12 [0.06-0.18]; p<0.001) or ACPA (0.34 [0.01-0.67]; p = 0.044) were significantly and independently associated with a higher DAS28 during follow-up, after adjusting for confounding variables such as gender, age and treatment. In addition, those patients with elevated sIL-15 had a significantly higher risk of receiving intensive treatment (RR 1.78, 95% confidence interval 1.18-2.7; p = 0.007).
CONCLUSIONS:
Patients with EA displaying high baseline sIL-15 suffered a more severe disease and received more intensive treatment. Thus, sIL-15 may be a biomarker for patients that are candidates for early and more intensive treatment.
Cereulide produced by Bacillus cereus increases fitness of the producer organism in low potassium environment.
Source
Dept Food and Environmental Science, Helsinki University;
Abstract
Cereulide, produced by certain Bacillus cereus strains, is a lipophilic cyclic peptide of 1152 Da that binds K+ ions with high specificity and affinity. It is toxic to humans, but its role for the producer organism is not known. We report here that cereulide operated for B. cereus as a tool to scavenge potassium when the environment is growth limiting for this ion. Cereulide producing B. cereus showed higher maximal growth rates (µmax) than cereulide non-producing B. cereus in K+ deficient medium, [K+] ~ 1 mM. The cereulide producing strains grew faster in K+ deficient than in K+ rich medium with or without added cereulide. Cereulide non-producing B. cereus neither increased µmax in K+ deficient medium compared to K+ rich medium, nor benefited from added cereulide. Cereulide producing strains outcompeted GFP-labeled B. thuringiensis in potassium deficient ([K+] ~1 mM) but not in potassium rich ([K+] ~30 mM) medium. Exposure to 2 µM of cereulide in potassium free medium void of energy source caused within seconds a major efflux of cellular K+ from B. cereus not producing cereulide and from B. subtilis. Cereulide depleted the cereulide non-producing B. cereus and B. subtilis cells of a major part of their K+ stores, but did not affect cereulide producing B. cereus strains. Externally added 6 - 10 µM cereulide triggered generation of biofilms and pellicles by B. cereus. The results indicate that both endogenous and externally accessible cereulide supported the fitness of the cereulide producing B. cereus in environments where potassium concentration is low.
- PMID:
- 22241046
- [PubMed - as supplied by publisher]
A dipeptidyl peptidase-4 inhibitor, des-fluoro-sitagliptin, improves endothelial function and reduces atherosclerotic lesion formation in apolipoprotein e-deficient mice.
Source
Department of Cardiovascular Medicine, Faculty of Life Sciences, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan; Department of Cardiovascular Clinical and Translational Research, Kumamoto University Hospital, Kumamoto, Japan.
Abstract
OBJECTIVES:
The aim of this study was to investigate the antiatherogenic effects of the dipeptidyl peptidase-4 inhibitor, des-fluoro-sitagliptin (DFS).
BACKGROUND:
The new class of anti-type 2 diabetes drugs, dipeptidyl peptidase-4 inhibitors, improves glucose metabolism by increasing levels of active glucagon-like peptide (GLP)-1.
METHODS:
Endothelial function was examined by acetylcholine-induced endothelium-dependent vasorelaxation using aortic rings and atherosclerotic lesion development in the entire aorta in apolipoprotein E-deficient mice fed a high-fat diet with or without DFS, and the antiatherogenic effects of DFS were investigated in cultured human macrophages and endothelial cells. Plasma levels of active GLP-1 were measured in patients with or without coronary artery disease.
RESULTS:
DFS significantly improved endothelial dysfunction (89.9 ± 3.9% vs. 79.2 ± 4.3% relaxation at 10(-4) mol/l acetylcholine, p < 0.05) associated with increased endothelial nitric oxide synthase phosphorylation and reduced atherosclerotic lesion area (17.7% [15.6% to 25.8%] vs. 24.6% [19.3% to 34.6%], p < 0.01) compared with vehicle treatment. In cultured human macrophages, DFS significantly increased GLP-1-induced cytosolic levels of cyclicadenosine monophosphate compared with GLP-1 alone, resulted in inhibiting phosphorylation of c-jun N-terminal kinase and extracellular signal-regulated kinase 1/2 and nuclear factor-kappa B p65 nuclear translocation through the cyclicadenosine monophosphate/protein kinase A pathway, and suppressed proinflammatory cytokines (i.e., interleukin-1-beta, interleukin-6, and tumor necrosis factor-alpha) and monocyte chemoattractant protein-1 production in response to lipopolysaccharide. DFS-enhanced GLP-1 activity sustained endothelial nitric oxide synthase phosphorylation and decreased endothelial senescence and apoptosis compared with GLP-1 alone. In the human study, fasting levels of active GLP-1 were significantly lower in patients with coronary artery disease than those without (3.10 pmol/l [2.40 to 3.62 pmol/l] vs. 4.00 pmol/l [3.10 to 5.90 pmol/l], p < 0.001).
CONCLUSIONS:
A DPP-4 inhibitor, DFS, exhibited antiatherogenic effects through augmenting GLP-1 activity in macrophages and endothelium.
Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Peptidyl-arginine deiminase: an additional marker of rheumatoid arthritis.
Source
Biotechnology Department, Heritage Institute of Technology, Chowbagha Road, Anandapur, Kolkata, India. psbasu.heritage@gmail.com
Abstract
BACKGROUND:
Antibodies against cyclic citrullinated peptide (anti-CCP) were thought to be more specific than rheumatoid factor (RF) for the diagnosis of rheumatoid arthritis (RA). The determination of anti-CCP in addition to RF could be helpful in the serological diagnosis and monitoring of patients with RA. Citrullination of proteins involves the enzymatic conversion of protein containing arginine residues to citrulline residues by the enzyme peptidylarginine deiminase (PAD). The present investigation was undertaken to estimate serum PAD enzyme activity in RA patients with a view to find its importance as a new diagnosis marker in a rheumatology clinic.
METHODS:
The activity of the PAD enzyme was measured by spectrophotometric method at 530 nm in sera of control subjects and in patients of RA (Group I: RF negative and CCP positive: Group II: both RF and CCP positive) in terms of citrulline formation using benzoyl-arginine ethyl ester (BAEE) as substrate. Anti-CCP and RF were also estimated in two groups by enzyme immunoassay and immunoturbidimetry for comparison. Clinical variables (duration of morning stiffness, swollen and tender joint counts, patient's assessment of pain) and C-reactive protein were also evaluated.
RESULTS:
A marked increase in PAD enzyme activity (p < 0.001) was noted in RA patients in comparison to controls and the level diminished appreciably along with two known serological markers (anti-CCP and RF) after six months of disease modifying antirheumatic drug (DMARD) treatment. The Group II RA patients showed much higher enzyme activity than Group I RA patients. However, clinical variables did not differ significantly between the two Groups of RA patients.
CONCLUSIONS:
We conclude that determination of PAD enzyme activity may be used as an additional marker for monitoring disease progression and regression along with anti-CCP and RF in patients with RA. Moreover, this method is rapid, sensitive, and inexpensive and can be adopted in a laboratory having modest facilities.
- PMID:
- 22239037
- [PubMed - in process]
Constrained α/γ-peptides: a new stable extended structure in solution without any hydrogen bond and characterized by a four-fold symmetry.
Source
Univ Paris-Sud, Laboratoire de Chimie des Procédés et Substances Naturelles, ICMMO, UMR 8182, CNRS, Bât 410, Orsay, F-91405, France. valerie.alezra@u-psud.fr.
Abstract
Small α/γ-peptides alternating α-aminoisobutyric acid and cyclic γ-amino acid residues are described. NMR studies together with restrained simulated annealing revealed that an extended backbone conformation largely dominates in solution for as short as 4-residues long oligomers. This new fold type is devoid of any hydrogen bond and characterized by a four-fold symmetry.
Targeted delivery of a novel palmitylated D-peptide for antiglioblastoma molecular therapy.
Source
School of Pharmacy, Key Laboratory of Smart Drug Delivery, Ministry of Education and PLA, Fudan University , Shanghai , China.
Abstract
Effective glioblastoma treatment with low toxicity is one of the most difficult challenges in cancer therapy. The interaction between tumor suppressor protein p53 and its negative regulator murine double minute 2 (MDM2) provides a promising target for specific therapy because an important subtype of glioblastoma harbors wild-type p53 and overexpressed MDM2. Several D-peptides have been previously reported to effectively antagonize MDM2 for binding to p53 with high affinity and unsurpassed specificity. However, poor cell penetration and lack of efficient delivery method hampered the therapeutic applicability of the most potent D-peptide, D-PMIβ. In this study, a novel lipophilic derivate of D-PMIβ (pDP) was developed. Liposome was chosen as a carrier for pDP, and cyclic pentapeptide c(RGDyK) was used as a targeting moiety for the treatment of glioblastoma. D-PMIβ was N-terminally modified with palmitic acid and the resultant c(RGDyK) decorated liposomes (RGD-liposomal pDP) showed almost 100% encapsulation efficiency and 10% loading efficiency. The abilities of palmitylated D-peptide to antagonize MDM2 and reactivate p53 specifically were confirmed by the western blot assay. The IC50 ratio of RGD-liposomal pDP in treating human umbilical vascular endothelial normal cells vs. U87 tumor cells was 10 times higher than that of RGD-liposomal doxorubicin. After intravenous administration, the median survival time of intracranial U87 glioblastoma-bearing nude mice treated with RGD-liposomal pDP (29 days) was significant longer than that of mice treated with blank RGD-liposome (23 days) (p<0.001). These results indicated that palmitylated D-peptide inhibitor of p53-MDM2 combined with RGD modified liposomes provided a potential molecular therapy for glioblastoma.
Human and rat hepatocyte toxicity and protein phosphatase 1 and 2A inhibitory activity of naturally occurring desmethyl-microcystins and nodularins.
Source
Food Chemistry and Toxicology, University of Kaiserslautern, Kaiserslautern 67659, Germany.
Abstract
Contamination of water, foods and food supplements by various genera of cyanobacteria is a serious health problem worldwide for humans and animals, largely due to the toxic effects of microcystins (MCs) and nodularin (NOD), a group of hepatotoxic cyclic peptides. The toxins occur in variable structures resulting in more than 90 different MCs and 8 different NODs, many of them not having been investigated for their toxic potency. Potent MCs such as MC-LR have been shown to elicit their hepatotoxic potency via inhibition of hepatic protein phosphatases (PP) 1 and 2A leading to over-phosphorylation of vital cellular proteins. This mechanism of action is also thought to be responsible for the long term tumor promoting action of certain MCs and NOD in the liver. Here, we report on the isolation of certain MCs and NOD as well as a number of their desmethylated derivatives from algae bloom. Subsequently, we determined the cytotoxicity of these compounds in isolated primary human and rat hepatocytes in culture. In parallel experiments, we analyzed the inhibitory potency of these congeners on PP1 and 2A using commercially available enzymes. We found in primary rat hepatocyts that MC-LR, -YR and NOD were more cytotoxic, namely in the 10 to >50nM range, while MC-RR was not. The desmethylated congeners of MC-LR, -YR, and NOD were equally or more-toxic as/than their fully methylated counterparts. In primary human hepatocytes we could show that MC-LR, NOD and the desmethylated variants [(3)Asp]MC-LR, [(7)Dha]MC-LR and [(1)Asp]NOD were cytotoxic in the 20 to >600nM range. Inhibition data with human, bovine and rabbit protein phosphatases 1 and 2A were roughly in accordance with the cytotoxicity findings in human and rat hepatocytes, i.e. desmethylation had no pronounced effects on the inhibitory potencies. Thus, a variety of naturally occurring desmethylated MC and NOD congeners have to be considered as being at least as toxic as the corresponding fully methylated derivatives.
Copyright © 2011. Published by Elsevier Ireland Ltd.
Engineering cyclic Peptide toxins.
Source
School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.
Abstract
Peptide-based toxins have attracted much attention in recent years for their exciting potential applications in drug design and development. This interest has arisen because toxins are highly potent and selectively target a range of physiologically important receptors. However, peptides suffer from a number of disadvantages, including poor in vivo stability and poor bioavailability. A number of naturally occurring cyclic peptides have been discovered in plants, animals, and bacteria that have exceptional stability and potentially ameliorate these disadvantages. The lessons learned from studies of the structures, stabilities, and biological activities of these cyclic peptides can be applied to the reengineering of toxins that are not naturally cyclic but are amenable to cyclization. In this chapter, we describe solid-phase chemical synthetic methods for the reengineering of peptide toxins to improve their suitability as therapeutic, diagnostic, or imaging agents. The focus is on small disulfide-rich peptides from the venoms of cone snails and scorpions, but the technology is potentially widely applicable to a number of other peptide-based toxins.
Copyright © 2012 Elsevier Inc. All rights reserved.
- PMID:
- 22230565
- [PubMed - in process]
Influence of natural and synthetic histone deacetylase inhibitors on chromatin.
Source
Parkville, Victoria, Australia; paul.licciardi@mcri.edu.au.
Abstract
Histone deacetylase inhibitors (HDACI) have emerged as a new class of anticancer therapeutics. The hydroxamic acid, suberoylanilide hyroxamic acid (Vorinostat, Zolinza™) and the cyclic peptide, depsipeptide (Romidepsin, Istodax™) were approved by the US Food and Drug Administration (FDA) for the treatment of cutaneous T-cell lymphoma in 2006 and 2009, respectively. At least 15 HDACI are currently undergoing clinical trials either alone or in combination with other therapeutic modalities for the treatment of numerous hematological and solid malignancies. Further, the potential utility of HDACI has been extended to non-oncologic applications including auto-immune disorders, inflammation, diseases of the central nervous system and malaria. Given the promise of HDACI, there is growing interest in the potential of dietary compounds that possess HDAC inhibition activity. This review is focused on the identification of and recent findings with HDACI from dietary, medicinal plant and microbial sources. We discuss the mechanisms of action and clinical potential of natural HDACI.
Effects of interferon-gamma liposomes targeted to platelet-derived growth factor receptor-beta on hepatic fibrosis in rats.
Source
Department of Gastroenterology, Zhongshan Hospital affiliated to Fudan University, Shanghai, China.
Abstract
No drugs have been approved clinically for the therapy of hepatic fibrosis. Though interferon-γ (IFN-γ) is a highly effective anti-fibrotic agent in vitro and in some animal models in vivo, its anti-fibrotic potential in clinical trials has been disappointing, due to unwanted off-target effects and a short half-life period which results in poor efficacy. The aims of this study are to develop a new targeted drug delivery system to selectively deliver IFN-γ to hepatic stellate cells (HSCs) and to investigate whether it will improve the anti-fibrotic effect of IFN-γ and reduce its side effects in fibrotic livers. Sterically stable liposomes (SSLs) were modified by cyclic peptides (pPB) with a specific affinity for platelet-derived growth factor receptor-β (PDGFR-β), and then IFN-γ was encapsulated in the targeted liposomes (pPB-SSL-IFN-γ). In vitro, pPB-SSL was found to be taken up and internalized by cultured activated HSCs. The binding of FITC-labeled pPB-SSL to activated HSCs was in a time-dependent and concentration-dependent manner, which could be inhibited by excess unlabelled pPB-SSL, PDGF-BB, suramin or monensin. The inhibitory effect of pPB-SSL-IFN-γ on the proliferation of activated HSCs was respectively 7.24-fold and 2.95-fold higher than that of free IFN-γ and IFN-γ encapsulated in untargeted SSLs. In healthy rats, the tissue distribution, living-body tracing image analyses and pharmacokinetics study showed that pPB-SSL-IFN-γ accumulated mainly in the livers and had a longer half-life than free IFN-γ (3.98±0.52h vs. 0.21±0.03h). Furthermore, in rats with hepatic fibrosis induced by thioacetamide injection, FITC-labeled pPB-SSL was found to predominantly localize in activated HSCs by immunofluorescent double staining for FITC and albumin or α-smooth muscle actin (α-SMA). The enhanced anti-fibrotic effect of pPB-SSL-IFN-γ treatnment was indicated by significant decreases in the histologic Ishak stage, collagen I-staining positive areas, and α-SMA expression levels in fibrotic livers. In addition, pPB-SSL-IFN-γ treatment improved the leukopenia caused by low- and high-dosage free IFN-γ treatments. In conclusion, IFN-γ encapsulated in pPB-SSL had an extended circulation half-life and was selectively delivered to activated HSCs, which enhanced the anti-fibrotic effect of IFN-γ and reduced its side-effects in rats with hepatic fibrosis. Thus, pPB-SSL-IFN-γ may be an effective agent for the therapy of hepatic fibrosis.
Copyright © 2011. Published by Elsevier B.V.
Unprecedented Occurrence of Isoaspartic Acid in a Plant Cyclopeptide.
Source
Molécules de Communication et Adaptation des Micro-Organismes, UMR 7245 CNRS, Muséum National d'Histoire Naturelle , 63 rue Buffon 75005 Paris, France, and Department of Botany, Makerere University , PO BOX 7062, Kampala, Uganda.
Abstract
Three structurally related cycloheptapeptides, cyclocitropsides A-C, have been isolated from a MeOH extract of the root bark of Citropsis articulata, a medicinal plant in Uganda. Their sequences were elucidated on the basis of their MS/MS fragmentation, extensive 2D-NMR, chemical degradation, and biochemical modifications. Surprisingly, the sequence of cyclocitropside C differed from that of cyclocitropside B only by an Asp(5)/isoAsp(5) substitution. This is the first report of an isoAsp residue in a plant cyclic peptide.
Structural Mass Spectrometry: Rapid Methods for Separation and Analysis ofPeptide Natural Products.
Source
Department of Chemistry, Vanderbilt University , Nashville, Tennessee, United States.
Abstract
A significant challenge in natural product discovery is the initial discrimination of discrete secondary metabolites alongside functionally similar primary metabolic cellular components within complex biological samples. A property that has yet to be fully exploited for natural product identification and characterization is the gas-phase collision cross section, or, more generally, the mobility-mass correlation. Peptide natural products possess many of the properties that distinguish natural products, as they are frequently characterized by a high degree of intramolecular bonding and possess extended and compact conformations among other structural modifications. This report describes a rapid structural mass spectrometry technique based on ion mobility-mass spectrometry for the comparison of peptide natural products to their primary metabolic congeners using mobility-mass correlation. This property is empirically determined using ion mobility-mass spectrometry, applied to the analysis of linear versus modified peptides, and used to discriminate peptide natural products in a crude microbial extract. Complementary computational approaches are utilized to understand the structural basis for the separation of primary metabolism derived linear peptides from secondary metabolite cyclic and modified cyclic species. These findings provide a platform for enhancing the identification of secondary metabolic peptides with distinct mobility-mass ratios within complex biological samples.
Anti-cyclic citrullinated peptide antibodies in scleroderma patients.
Source
Rheumatology Unit, Evangelical University Hospital of Curitiba, Curitiba, Paraná, Brazil.
Abstract
Anti-CCP (cyclic citrullinated peptide) is considered the most useful laboratory tool in the diagnosis of rheumatoid arthritis (RA). Some authors have also found this autoantibody in patients with scleroderma (SSc). The study aimed to investigate the prevalence of anti-CCP antibodies in SSc patients from Southern Brazil and their association with clinical and serological profile of the disease. We studied 76 patients with SSc and 100 healthy volunteers for presence of anti-CCP. SSc patients charts were reviewed for clinical and laboratory data. In the SSc group, the diffuse form was present in 20.5%; 62.8% had the limited form; 14.1% had overlap with systemic lupus or polymyositis and 2.5% had SSc sine scleroderma. Anti-CCP was found in nine of 78 (11.5%) SSc patients and in one of 100 healthy volunteers (p = 0.0054). No relationship was found with arthritis, skin Rodnan m score, esophageal dysmotility, myocarditis, pulmonary hypertension and lung fibrosis. Positive association was observed with arthralgias (p = 0.02). Also, no relationship was noted with the presence of anti-centromere antibodies, anti-Scl-70, anti-RNP or rheumatoid factor. Anti-CCP are more common in SSc patients than in controls. Arthralgias but not arthritis or rheumatoid factor are more frequent in anti-CCP positive patients.
Interaction of the non-phosphorylated peptide G7-18NATE with Grb7-SH2 domain requires phosphate for enhanced affinity and specificity.
Source
Department of Biochemistry and Molecular Biology, Monash University, VIC, 3800, Australia.
Abstract
Src-homology (SH2) domains are an attractive target for the inhibition of specific signalling pathways but pose the challenge of developing a truly specific inhibitor. The G7-18NATE cyclic peptide is reported to specifically inhibit the growth factor receptor bound protein 7 (Grb7) adapter protein, implicated in the progression of several cancer types, via interactions with its SH2 domain. G7-18NATE effectively inhibits the interaction of Grb7 with ErbB3 and focal adhesion kinase in cell lysates and, with the addition of a cell permeability sequence, inhibits the growth and migration of a number of breast cancer cell lines. It is thus a promising lead in the development of therapeutics targeted to Grb7. Here we investigate the degree to which G7-18NATE is specific for the Grb7-SH2 domain compared with closely related SH2 domains including those of Grb10, Grb14, and Grb2 using surface plasmon resonance. We demonstrate that G7-18NATE binds with micromolar binding affinity to Grb7-SH2 domain (K(D) = 4-6 μm) compared with 50-200 times lower affinity for Grb10, Grb14, and Grb2 but that this specificity depends critically on the presence of phosphate in millimolar concentrations. Other differences in buffer composition, including use of Tris or 2-(N-Morpholino)ethanesulfonic acid or varying the pH, do not impact on the interaction. This suggests that under cellular conditions, G7-18NATE binds with highest affinity to Grb7. In addition, our findings demonstrate that the basis of specificity of G7-18NATE binding to the Grb7-SH2 domain is via other than intrinsic structural features of the protein, representing an unexpected mode of molecular recognition. Copyright © 2011 John Wiley & Sons, Ltd.
Copyright © 2011 John Wiley & Sons, Ltd.
Should rheumatoid factor in rheumatoid arthritis be sent to Davy Jones's Locker?
Source
Department of Rheumatology, University Hospital of North Norway , Tromsø , Norway.
Abstract
This article reviews the characteristics and weaknesses of the rheumatoid factor (RF) assay compared with anti-citrullinated peptide antibody (ACPA) testing in the work-up of patients with synovitis. This should lead physicians to change their ordering habits and replace RF by ACPA. For RA diagnosis, good clinical judgement based on clinical history, physical examination and routine laboratory work exceeds the value of RF and ACPA assays. In settings of both low and high pretest probability, the added value of each of these assays is low. In cases with intermediate probability, ACPA assays are superior to immunoglobulin (Ig)M-RF because of their higher specificity, and they should be the first choice in a RA diagnostic work-up. Dual testing brings few additional advantages and increases costs significantly. ACPA and IgM-RF are both imperfect tests; around 30% of patients with manifest RA will test negative in both assays and therefore caution needs to be exercised when interpreting negative results. Since 2009, the anti-cycliccitrullinated peptide (anti-CCP) antibody assay has been the only assay available at our institution for RA work-up, with IgM-RF available on a case-by-case basis for non-RA diseases. This has led to a 70% reduction in RF assays performed annually.
No comments:
Post a Comment