1.
Bacillus subtilis RapA phosphatase domain interaction with its substrate Spo0F~P and inhibitor PhrA peptide.
Source
The Scripps Research Institute, Department of Molecular and Experimental Medicine, 10550 North Torrey Pines Road, MEM-116, La Jolla, CA 92037.
Abstract
Rap proteins in Bacillus subtilis regulate the phosphorylation level or the DNA-binding activity of response regulators such as Spo0F, involved in sporulation initiation, or ComA, regulating competence development. Rap proteins can be inhibited by specific peptides generated by the export-import processing pathway of the Phr proteins. Rap proteins have a modular organization comprising an amino terminal alpha-helical domain connected to a domain formed by six tetratricopeptide (TPR) repeats. In this study, the molecular basis for the specificity of the RapA phosphatase for its substrate Spo0F∼P and its inhibitor pentapeptide PhrA was analyzed in part by generating chimeric proteins with RapC that targets the DNA-binding domain of ComA, rather than Spo0F∼P, and is inhibited by the PhrC pentapeptide. In vivo analysis of sporulation efficiency or competence-induced gene expression as well as in vitro biochemical assays allowed the identification of the amino terminal sixty amino acids as sufficient to determine Rap specificity for its substrate and the central TPR3-5 repeats as providing binding specificity toward the Phr peptide inhibitor. The results allowed the prediction and testing of key residues in RapA that are essential for PhrA binding and specificity, thus demonstrating how the widespread structural fold of the TPR repeat is highly versatile to use a common interaction mechanism for a variety of functions in eukaryotic and prokaryotic organisms.
Vasoactive Peptides with Angiogenesis-Regulating Activity Predict Cancer Risk in Males.
Source
Authors' Affiliations: 1Department of Clinical Sciences, Lund University, Section of Oncology, Lund; 2Department of Clinical Sciences, Lund University, Malmö; Department of 3Oncology, 4Surgery, and 5Center of Emergency Medicine, Skåne University Hospital, Lund and Malmö, Sweden; 6BRAHMS Biomarkers, Thermo Fisher Scientific, Hennigsdorf; 7Waltraut Bergmann Foundation, Hohen Neuendorf, Germany; 8Cardiology Division, Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston; 9Broad Institute of Harvard and MIT, Cambridge; and 10Framingham Heart Study, Framingham, Massachusetts.
Abstract
BACKGROUND:
Tumor development requires angiogenesis, and antiangiogenesis has been introduced in the treatment of cancer patients; however, how the cardiovascular phenotype correlates with cancer risk remains ill-defined. Here, we hypothesized that vasoactive peptides previously implicated in angiogenesis regulation predict long-term cancer risk.
METHODS:
We measured midregional proatrial natriuretic peptide (MR-proANP), proadrenomedullin (MR-proADM), and C-terminal preprovasopressin (copeptin) in fasting plasma from participants of the Malmö Diet and Cancer Study that were free from cancer prior to the baseline exam in 1991 to 1994 (1,768 males and 2,293 females). We used Cox proportional hazards models to determine the time to first cancer event in relation to baseline levels of vasoactivepeptides during a median follow-up of 15 years.
RESULTS:
First cancer events occurred in 366 males and in 368 females. In males, one SD increase of MR-proANP, copeptin, and MR-proADM was independently related to incident cancer [HR (95% CI)] by 0.85 (0.74-0.96), P = 0.012; 1.17 (1.04-1.32), P = 0.009; and 1.12 (0.99-1.26), P = 0.065, respectively, and a summed biomarker score identified an almost 2-fold difference in cancer risk between the top and bottom quartile (P < 0.001). In younger males, the biomarker score identified a more than 3-fold increase in risk between the top and bottom quartile (P < 0.001). Among females, we found no relationship between biomarkers and cancer incidence.
CONCLUSIONS:
Our data suggest that vasoactive peptide biomarkers predict cancer risk in males, particularly in younger males.Impact: Our findings may have implications for cancer risk prediction and present novel, potentially drug modifiable, mechanisms underlying cancer development. Cancer Epidemiol Biomarkers Prev; 1-10. ©2012 AACR.
Molecular Changes Induced in Rat Liver by Hemorrhage and Effects of Melanocortin Treatment.
Source
* Postdoctoral Fellow, Center for Surgical Research, ** Director, Center for Preclinical Investigation, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milano, Italy. † Assistant Professor of Pharmacology, ‡Postgraduate Student, # Postdoctoral Fellow, †† Full Professor of Pharmacology, Department of Biomedical Sciences, Section of Pharmacology, University of Modena and Reggio Emilia, Modena, Italy. §Research Assistant, Department of Internal Medicine, University of Milano, Milano, Italy. ‖ Associate Professor of Pharmaceutical Chemistry, Department of Pharmaceutical Chemistry and Toxicology, University of Napoli "Federico II," Napoli, Italy.
Abstract
BACKGROUND:
Melanocortin peptides improve hemodynamic parameters and prevent death during severe hemorrhagic shock. In the present research we determined influences of a synthetic melanocortin 1/4 receptor agonist on the molecular changes that occur in rat liver during hemorrhage.
METHODS:
Controlled-volume hemorrhage was performed in adult rats under general anesthesia by a stepwise blood withdrawal until mean arterial pressure fell to 40 mmHg. Then rats received either saline or the synthetic melanocortin 1/4 receptor agonist Butir-His-D-Phe-Arg-Trp-Sar-NH2 (Ro27-3225; n = 6-8 per group). Hemogasanalysis was performed throughout a 60-min period. Gene expression in liver samples was determined at 1 or 3 h using quantitative real-time polymerase chain reaction.
RESULTS:
At 1 h, in saline-treated shocked rats, there were significant increases in activating transcription factor 3 (Atf3), early growth response 1 (Egr1), heme oxygenase (decycling) 1 (Hmox1), FBJ murine osteosarcoma viral oncogene homolog (Fos), and jun oncogene (Jun). These changes were prevented by Ro27-3225 (mean ± SEM: Atf3 152.83 ± 58.62 vs. 579.00 ± 124.13, P = 0.002; Egr1 13.21 ± 1.28 vs. 26.63 ± 1.02, P = 0.001; Hmox1 3.28 ± 0.31 vs. 166.54 ± 35.03, P = 0.002; Fos 4.36 ± 1.03 vs. 14.90 ± 3.44, P < 0.001; Jun 6.62 ± 1.93 vs. 15.07 ± 2.09, P = 0.005; respectively). Increases in alpha-2-macroglobulin (A2m), heat shock 70kD protein 1A (Hspa1a), erythropoietin (Epo), and interleukin-6 (Il6) occurred at 3 h in shocked rats and were prevented by Ro27-3225 treatment (A2m 6.90 ± 0.82 vs. 36.73 ± 4.00, P < 0.001; Hspa1a 10.34 ± 3.28 vs. 25.72 ± 3.64, P = 0.001; Epo 0.49 ± 0.13 vs. 2.37 ± 0.73, P = 0.002; Il6 1.05 ± 0.15 vs. 1.88 ± 0.23, P < 0.001; respectively). Further, at 3 h in shocked rats treated with Ro27-3225 there were significant increases in tight junction protein 1 (Tjp1; 27.30 ± 2.43 vs. 5.03 ± 1.68, P < 0.001) and nuclear receptor subfamily 4, group A, member 1 (Nr4a1; 91.03 ± 16.20 vs. 30.43 ± 11.0, P = 0.01) relative to sham animals. Treatment with Ro27-3225 rapidly restored blood pressure, hemogasanalysis parameters, and lactate blood levels.
CONCLUSIONS:
Melanocortin treatment significantly prevents most of the systemic and hepatic detrimental changes induced by hemorrhage.
Accuracy of Diagnostic Antibody Tests for Coeliac Disease in Children: Summary of an Evidence Report.
Source
*Centre for Social Policy Research, University of Bremen, Bremen †Medical Review Board of the Statutory Health Insurance Funds (MDS), Essen, Germany ‡Epidemiology and Biostatistics Unit, Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy §Dr von Haunersches Kinderspital, Ludwig Maximilians Universität München, München, Germany ||Hans Christian Andersen Children's Hospital, Odense University Hospital, Odense C, Denmark ¶Department of Paediatrics, Medical and Health Science Centre, University of Debrecen, Debrecen, Hungary #Heim Pal Children's Hospital, Budapest, Hungary.
Abstract
OBJECTIVE:
The aim of this study was to summarise the evidence from 2004 to September 2009 on the performance of laboratory-based serological and point of care (POC) tests for diagnosing coeliac disease (CD) in children using histology as reference standard.
PATIENTS AND METHODS:
We searched MEDLINE and EMBASE for studies reporting on children for tests based on IgA and IgG anti-gliadin (AGA), endomysial (EmA), anti-transglutaminase-2 (TG2), and anti-deamidated gliadin peptides(DGP) antibodies or POC tests. For inclusion, histological analysis of duodenal biopsies and sensitivity and specificity for index tests had to be reported. Data were pooled and summary measures calculated for sensitivity, specificity, positive and negative likelihood ratios ("LR+", "LR-"), and diagnostic odds ratios (DOR). In case of elevated statistical heterogeneity, studies reaching 90% sensitivity or specificity were reported.
RESULTS:
A total of 2510 articles were reviewed; 16 entered meta-analysis, reporting on 3110 patients (1876 with CD, 1234 without CD). For IgA-EmA, sensitivity was ≥90% in 7/11 studies and pooled specificity 98.2%. For IgA-anti-TG2, 11/15 studies yielded sensitivities ≥90% and 13/15 specificities ≥90%. For IgA-DGP, sensitivity ranged between 80.7% and 95.1% (specificity 86.3%-93.1%); for IgG-DGP between 80.1% and 98.6% (specificity 86.0-96.9%). IgA-EmA had the highest pooled DOR (554) and LR+ (31.8) for a laboratory test, followed by IgA-anti-TG2, IgG-DGP, IgA-DGP and IgA-AGA. POC tests showed a pooled sensitivity of 96.4% for IgA-TG2 (specificity 97.7%).
CONCLUSIONS:
IgA-EmA and IgA-anti-TG2 tests appear highly accurate to diagnose CD. IgG-anti-DGP tests may help in excluding CD. IgA-AGA and IgA-DGP tests show inferior accuracy. POC tests may achieve high accuracy in the hands of experienced readers, but IgA-anti-TG2/EmA were superior.
A luminescent affinity tag for proteins based on the terbium(III)-binding peptide.
Source
Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan; Research Center for Bio-Microsensing Technology, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu 804-8550, Japan.
Abstract
Genetically encoded tags attached to proteins of interest are widely exploited for proteome analysis. Here, we present Tb(3+)-binding peptides (TBPs) which can be used for both luminescent measurements and affinity purification of proteins. TBPs consist of acidic amino acid residues and tryptophan residues which serve as Tb(3+)-binding sites and sensitizers for Tb(3+) luminescence, respectively. The Tb(3+) complexes of TBPs fused to a target protein exhibited luminescence characteristic of Tb(3+) by excitation of the tryptophan residue, and fusion proteins fused to one of the TPBs were successfully isolated from Escherichia coli cell lysate by affinity chromatography with a Tb(3+)-immobilized solid support.
Copyright © 2012 Elsevier Inc. All rights reserved.
IL-22 Mediates Host Defense against an Intestinal Intracellular Parasite in the Absence of IFN-γ at the Cost of Th17-Driven Immunopathology.
Source
Molekulare Parasitologie, Humboldt Universität zu Berlin, D-10115 Berlin, Germany;
Abstract
The roles of Th1 and Th17 responses as mediators of host protection and pathology in the intestine are the subjects of intense research. In this study, we investigated a model of intestinal inflammation driven by the intracellular apicomplexan parasite Eimeria falciformis. Although IFN-γ was the predominant cytokine during E. falciformis infection in wild-type mice, it was found to be dispensable for host defense and the development of intestinal inflammation. E. falciformis-infected IFN-γR(-/-) and IFN-γ(-/-) mice developed dramatically exacerbated body weight loss and intestinal pathology, but they surprisingly harbored fewer parasites. This was associated with a striking increase in parasite-specific IL-17A and IL-22 production in the mesenteric lymph nodes and intestine. CD4(+) T cells were found to be the source of IL-17A and IL-22, which drove the recruitment of neutrophils and increased tissue expression of anti-microbialpeptides (RegIIIβ, RegIIIγ) and matrix metalloproteinase 9. Concurrent neutralization of IL-17A and IL-22 in E. falciformis-infected IFN-γR(-/-) mice resulted in a reduction in infection-induced body weight loss and inflammation and significantly increased parasite shedding. In contrast, neutralization of IL-22 alone was sufficient to increase parasite burden, but it had no effect on body weight loss. Treatment of an E. falciformis-infected intestinal epithelial cell line with IFN-γ, IL-17A, or IL-22 significantly reduced parasite development in vitro. Taken together, to our knowledge these data demonstrate for the first time an antiparasite effect of IL-22 during an intestinal infection, and they suggest that IL-17A and IL-22 have redundant roles in driving intestinal pathology in the absence of IFN-γ signaling.
Preliminary evaluation of a microwave-assisted metal-labeling strategy for quantification of peptides via RPLC-ICP-MS and the method of standard additions.
Source
National Institute of Standards and Technology, Material Measurement Laboratory, Analytical Chemistry Division, 331 Fort Johnson Road, Charleston, SC 29412, United States.
Abstract
NIST has performed preliminary research on applying a calibration methodology based on the method of standard additions to the quantification of peptides via reverse-phase liquid chromatography coupled to inductively coupled plasma mass spectrometry (RPLC-ICP-MS). A microwave-assisted lanthanide labeling procedure was developed and applied to derivatize peptides using the macrocyclic bifunctional chemical chelator DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), which significantly improved the lanthanide labeling yield and reduced reaction times compared to benchtop labeling procedures. Biomolecular MS technologies of matrix-assisted laser desorption ionization (MALDI)-MS and electrospray ionization (ESI)-MS/MS were used in concert with ICP-MS to confirm the results of microwave labeling, sample cleanup and standard additions experiments for several test peptides. The calibration scheme is outlined in detail and contextualized against complementary high accuracy calibration strategies currently employed for ICP-MS detection of biomolecules. Standard additions experiments using native, non-isotopic peptide calibrants confirm the simplicity of the scheme and the potential of applying a blending (recombined sample and spike) procedure, facilitating calibration via co-elution of lanthanide labeled peptides. Ways to improve and fully leverage the analytical methodology are highlighted.
Published by Elsevier B.V.
JBIR-78 and JBIR-95: Phenylacetylated Peptides Isolated from Kibdelosporangium sp. AK-AA56.
Source
Biomedicinal Information Research Center (BIRC), Japan Biological Informatics Consortium (JBIC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.
Abstract
The search for metabolites of Kibdelosporangium sp. AK-AA56 resulted in the discovery of novel N-phenylacetylatedpeptides, JBIR-78 (1) and JBIR-95 (2). Compounds 1 and 2 were established to be N-phenylacetylated heptapeptides by extensive NMR and HRESIMS analyses. The absolute configuration of the standard amino acids including a cysteic acid moiety was determined using Marfey's method on the acid hydrolysates of 1 and 2. The relative and absolute configurations of a nonstandard amino acid, β-hydroxyleucine, were elucidated using the J-based and modified Mosher's methods, respectively. In an antimicrobial test, 1 showed antibacterial activity against Micrococcus luteus.
Effects of soybean peptide and collagen peptide on collagen synthesis in normal human dermal fibroblasts.
Source
Faculty of Pharmaceutical Sciences, Josai University , 1-1 Keyakidai, Sakado, Saitama, 350-0295 , Japan.
Abstract
The collagen present in the dermis of the skin is a fibrous protein that fills the gaps between cells and helps maintain tissue flexibility. Effectively increasing the collagen present in the skin is an important goal for cosmetic research. Recent research has shown that soybean peptide (SP) has anti-fatigue activity, antioxidant activity, and the ability to increase type I collagen, while collagen peptide (CP) has the ability to enhance corneal moisture content and viscoelasticity, as well as to increase levels of hyaluronic acid synthesizing enzymes in human skin. Little documentedresearch, however, has been conducted on collagen formation in relation to these peptides. Therefore, this researchapplied SP and CP with molecular weights primarily around 500 and preparations containing both SP and CP to normal human dermal fibroblasts together with magnesium ascorbyl phosphate (VC-PMg), and used real-time PCR to determine the gene expression of type I collagen (COL1A1), which contributes to collagen synthesis, and Smad7, which contribute to collagen breakdown. In addition, enzyme linked immuno sorbent assay (ELISA) was used to measure collagen content in the media. COL1A1 gene expression at 24 h after sample addition showed higher tendency in all samples and increased with time at 4, 8 and 24 h after addition. Smad7 gene expression was not substantially different at 4 h after addition. matrix metalloproteinase-1 gene expression was higher following SP addition, but was lower after the addition of CP and SP+CP. Medium collagen content was higher in all samples and increased with time at 8 h after addition. Collagen levels were higher when SP and CP were added together.
Surveying proteolytic processes in human cancer microenvironments by microdialysis and activity-based mass spectrometry.
Source
Boston Biomedical Research Institute, Watertown, MA, USA. hardt@bbri.org.
Abstract
Purpose: We present a strategy to survey proteolytic processes that occur in human cancer microenvironments. Experimental design: In situ microdialysis during oral cancer surgery was combined with mass spectrometry-based proteomics to analyze interstitial fluid surrounding tumors and anatomically matched normal sites. Protease activity-based (18)O-profiling was utilized to reveal peptides that were processed by co-collected proteases ex vivo. Results: We demonstrated for the first time the use of microdialysis in humans to collect interstitial fluid from cancer microenvironments. Proteomic profiling identified proteases and inhibitors in the microdialysis samples. A subset ofpeptides displayed characteristic (18)O-isotope patterns that indicated processing by endogenous proteases. Conclusions and clinical relevance: The presented approach provides unprecedented views of in vivo targets of proteases without disrupting the cancer or surrounding tissue. The methodology can be broadly adapted to other physiological conditions in which proteolytic mediators are involved (e.g. arthritic joints, inflamed muscle, other types of cancer) and where a comparison of normal and pathological tissue is sought.
Copyright © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.
- PMID:
- 22262628
- [PubMed - in process]
Roles of tRNA in cell wall biosynthesis.
Source
Department of Microbiology, Ohio State University, Columbus, OH, USA.
Abstract
Recent research into various aspects of bacterial metabolism such as cell wall and antibiotic synthesis, degradation pathways, cellular stress, and amino acid biosynthesis has elucidated roles of aminoacyl-transfer ribonucleic acid (aa-tRNA) outside of translation. Although the two enzyme families responsible for cell wall modifications, aminoacyl-phosphatidylglycerol synthases (aaPGSs) and Fem, were discovered some time ago, they have recently become of intense interest for their roles in the antimicrobial resistance of pathogenic microorganisms. The addition of positively charged amino acids to phosphatidylglycerol (PG) by aaPGSs neutralizes the lipid bilayer making the bacteria less susceptible to positively charged antimicrobial agents. Fem transferases utilize aa-tRNA to form peptide bridges that link strands of peptidoglycan. These bridges vary among the bacterial species in which they are present and play a role in resistance to antibiotics that target the cell wall. Additionally, the formation of truncated peptides results in shorter peptide bridges and loss of branched linkages which makes bacteria more susceptible to antimicrobials. A greater understanding of the structure and substrate specificity of this diverse enzymatic family is necessary to aid current efforts in designing potential bactericidal agents. These two enzyme families are linked only by the substrate with which they modify the cell wall, aa-tRNA; their structure, cell wall modification processes and the physiological changes they impart on the bacterium differ greatly. WIREs RNA 2012. doi: 10.1002/wrna.1108 For further resources related to this article, please visit the WIREs website.
Copyright © 2012 John Wiley & Sons, Ltd.
A universal strategy for preparing protected C-terminal peptides on the solid phase through an intramolecular click chemistry-based handle.
Source
Institute for Research in Biomedicine, Barcelona Science Park (PCB), Baldiri Reixac 10, 08028-Barcelona, Spain. albericio@irbbarcelona.org judit.tulla@irbbarcelona.org.
Abstract
A new universal strategy exploits DKP formation in a dipeptide moiety whose C-terminal residue is blocked by a leaving group. It enables both synthesis of C-terminal protected peptides that are useful for convergent synthesis of largepeptides and use of a C-terminal permanent protecting group that can be cleaved by catalytic hydrogenation to release the peptide.
Peptides and their potential role in the treatment of diabetes and obesity.
Source
Section of Investigative Medicine, Department of Medicine, Imperial College London, London, UK.
Abstract
It is estimated that 347 million people worldwide have diabetes and that over 1.5 billion adults worldwide are overweight. Predictions suggest these rates are increasing. Diabetes is a common complication in overweight and obese subjects, and in 2004, an estimated 3.4 million people died from consequences of high blood sugar. Thus, there is great interest in revealing the physiological systems that regulate body weight and blood sugar. Several peptidergic systems within the central nervous system and the periphery regulate energy homeostasis. A number of these systems have been investigated as potential treatments for obesity and the metabolic syndrome. However, manipulation of peptidergic systems poses many problems. This review discusses the peptidergic systems currently attracting research interest for their clinical potential to treat obesity. We consider first neuropeptides in the brain, including the orexigenic neuropeptide Y and melanin-concentrating hormone, and anorectic factors such as the melanocortins, ciliary neurotrophic factor, and neuromedin U. We subsequently discuss the utility of targeting peripheral gut peptides, including pancreatic polypeptide, peptide YY, amylin, and the gastric hormone ghrelin. Also, we analyze the evidence that these factors or drugs based on them may be therapeutically useful, while considering the disadvantages of using such peptides in a clinical context.
Therapy for obesity based on gastrointestinal hormones.
Source
Diabetes Research Division, Department of Internal Medicine F, Gentofte Hospital, University of Copenhagen, Denmark.
Abstract
It has long been known that peptide hormones from the gastrointestinal tract have significant impact on the regulation of nutrient metabolism. Among these hormones, incretins have been found to increase insulin secretion, and thus incretin-based therapies have emerged as new modalities for the treatment of type 2 diabetes. In contrast to other antidiabetic treatments, these agents have a positive outcome profile on body weight. Worldwide there are 500 million obese people, and 3 million are dying every year from obesity-related diseases. Recently, incretin-based therapy was proposed for the treatment of obesity. Currently two different incretin therapies are widely used in the treatment of type 2 diabetes: 1) the GLP-1 receptor agonists which cause significant and sustained weight loss in overweight patients, and 2) dipeptidyl peptidase 4 (DPP-4) inhibitors being weight neutral. These findings have led to a greater interest in the physiology of intestinal peptides with potential weight-reducing properties. This review discusses the effects of the incretin-based therapies in obesity, and provides an overview of intestinal peptides with promising effects as potential new treatments for obesity.
Evaluation of the long-term effects of gastric inhibitory polypeptide-ovalbumin conjugates on insulin resistance, metabolic dysfunction, energy balance and cognition in high-fat-fed mice.
Source
School of Biomedical Sciences Research Institute, SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine BT52 1SA, UK.
Abstract
The effects of active immunisation with gastric inhibitory polypeptide (GIP) or (proline3)GIP-ovalbumin conjugates on insulin resistance, metabolic dysfunction, energy expenditure and cognition were examined in high-fat-fed mice. Normal mice were injected (subcutaneously) once every 14 d for 98 d with GIP-ovalbumin conjugates, with transfer to a high-fat diet on day 21. Active immunisation resulted in GIP antibody generation and significantly (P < 0·01 to P < 0·001) reduced circulating non-fasting plasma insulin concentrations compared to high-fat control mice from day 70 onwards. The glycaemic responses to intraperitoneal glucose or nutrient ingestion were significantly improved in all treated mice, with corresponding stimulated plasma insulin levels depressed compared to high-fat controls. These changes were associated with substantially (P < 0·001) improved glucose-lowering responses to exogenous insulin and decreases of muscle and fat TAG, pancreatic insulin, circulating total and LDL-cholesterol levels (P < 0·01 to P < 0·001). Treatment with GIP-ovalbumin conjugates was not associated with alterations in energy expenditure, indirect calorimetry or aspects of cognitive function. The observed changes were almost identical in GIP and (Pro3)GIP immunised mice and were independent of any effects on food intake or body weight. Further tests established that coupling of GIP peptides to ovalbumin abolished any intrinsic insulin-releasing or glucose-lowering activity. These results suggest that induction of GIP-neutralising antibodies with GIP-ovalbumin conjugates is an effective means of countering the metabolic abnormalities induced by high-fat feeding and does not adversely have an impact on a marker of cognition function or energy expenditure.
Exploiting cell surface thiols to enhance cellular uptake.
Source
Medical Research Council, Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.
Abstract
Efficient cellular delivery is one of the key issues that has hampered the therapeutic development of novel synthetic biomolecules such as oligonucleotides, peptides and nanoparticles. The highly specialized cellular plasma membrane specifically internalizes compounds through tightly regulated mechanisms. It is possible to exploit these natural mechanisms of cellular uptake with rationally designed reagents. Here, we discuss how thiol groups (-SH) naturally present on the cell surface (exofacial thiols) can be used to enhance cellular association and internalization of various materials bearing thiol-reactive groups in their structure. We propose that such thiol modifications should be considered in future design of synthetic biomolecules for optimized cellular delivery.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Bioengineered nisin derivatives with enhanced activity in complex matrices.
Source
Department of Microbiology Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
Abstract
Nisin A is the best known and most extensively characterized lantibiotic. As it is ribosomally synthesized, bioengineering-based strategies can be used to generate variants. We have previously demonstrated that bioengineering of the hinge region of nisin A can result in the generation of variants with enhanced anti-microbial activity against Gram-positive pathogens. Here we created a larger bank of hinge variant producers and screened for producers that exhibit enhanced bioactivity as assessed by agar-based assays against a selection of target strains. Further analysis of 12 'lead' variants reveals that in many cases enhanced bioactivity is not attributable to enhanced specific activity but is instead as a consequence of an enhanced ability to diffuse through complex polymers. In the case of two variants, which contain the residues SVA and NAK, respectively, within the hinge region, we demonstrate that this enhanced trait enables the peptides to dramatically outperform nisin A with respect to controlling Listeria monocytogenes in commercially produced chocolate milk that contains carrageenan as a stabilizer.
© 2012 The Authors. Microbial Biotechnology © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.
- PMID:
- 22260415
- [PubMed - as supplied by publisher]
EGFR ligands exhibit functional differences in models of paracrine and autocrine signaling.
Source
Purdue University College of Pharmacy and Purdue University Center for Cancer Research , West Lafayette, IN 47907-2064 , USA.
Abstract
Epidermal growth factor (EGF) family peptides are ligands for the EGF receptor (EGFR). Here, we elucidate functional differences among EGFR ligands and mechanisms underlying these distinctions. In 32D/EGFR myeloid and MCF10A breast cells, soluble amphiregulin (AR), transforming growth factor alpha (TGFα), neuregulin 2 beta, and epigen stimulate greater EGFR coupling to cell proliferation and DNA synthesis than do EGF, betacellulin, heparin-binding EGF-like growth factor, and epiregulin. EGF competitively antagonizes AR, indicating that its functional differences reflect dissimilar intrinsic activity at EGFR. EGF stimulates much greater phosphorylation of EGFR Tyr1045 than does AR. Moreover, the EGFR Y1045F mutation and z-cbl dominant-negative mutant of the c-cbl ubiquitin ligase potentiate the effect of EGF but not of AR. Both EGF and AR stimulate phosphorylation of EGFR Tyr992. However, the EGFR Y992F mutation and phospholipase C gamma inhibitor U73122 reduce the effect of AR much more than that of EGF. Expression of TGFα in 32D/EGFR cells causes greater EGFR coupling to cell proliferation than does expression of EGF. Moreover, expression of EGF in 32D/EGFR cells causes these cells to be largely refractory to stimulation with soluble EGF. Thus, EGFR ligands are functionally distinct in models of paracrine and autocrine signaling and EGFR coupling to biological responses may be specified by competition among functionally distinct EGFR ligands.
Food protein-derived bioactive peptides: production, processing, and potential health benefits.
Source
Authors are with Dept. of Human Nutritional Sciences and author Aluko is also with the Richardson Centre for Functional Foods and Nutraceuticals, Univ. of Manitoba, 196 Innovation Drive, Winnipeg, MB R3T 2N2, Canada. Author Udenigwe is also with Dept. of Food Science, Univ. of Guelph, Guelph, ON N1G 2W1, Canada. Direct inquiries to author Aluko (E-mail: alukor@cc.umanitoba.ca).
Abstract
Bioactive peptides (BAPs), derived through enzymatic hydrolysis of food proteins, have demonstrated potential for application as health-promoting agents against numerous human health and disease conditions, including cardiovascular disease, inflammation, and cancer. The feasibility of pharmacological application of these peptidesdepends on absorption and bioavailability in intact forms in target tissues, which in turn depends on structure of thepeptides. Therefore, production and processing of peptides based on important structure-function parameters can lead to the production of potent peptides. This article reviews the literature on BAPs with emphasis on strategic production and processing methods as well as antihypertensive, anticancer, anticalmodulin, hypocholesterolemic, and multifunctional properties of the food protein-derived peptides. It is recommended that future research efforts on BAP should be directed toward elucidation of their in vivo molecular mechanisms of action, safety at various doses, and pharmacological activity in maintaining homeostasis during aberrant health conditions in human subjects.
© 2011 Institute of Food Technologists®
[Research progress in fusion expression of antimicrobial peptides].
Source
Laboratory of Feed Biotechnology, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing 100193, China.
Abstract
Antimicrobial peptides (AMPs) are of great significance in the field of food, feed and medicine due to their wide spectrum of antimicrobial activity and new mechanism of action different from conventional antibiotics. AMPs production from natural sources is usually limited, and chemical synthesis is not economically practical, especially for the production of long peptides. Therefore, heterologous expression of AMPs has been widely studied as an alternative, and fusion expression plays an important role in increasing production. The present review mainly focuses on the types and bioactivities of AMPs. In addition, the recent strategies to the most commonly used carrier proteins for fusion expression of AMPs and prospects for future research were also discussed.
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