1.
Effects of Cord Serum Insulin, IGF-II, IGFBP-2, IL-6 and Cortisol Concentrations on Human Birth Weight and Length: Pilot Study.
Source
Department of Paediatrics, University Hospital of Parma, Parma, Italy.
Abstract
BACKGROUND:
The IGF system is recognised to be important for fetal growth. We previously described increased Insulin-like growth factor binding protein (IGFBP)-2 cord serum concentrations in intra-uterine growth retardation (IUGR) compared with appropriate for gestational age (AGA) newborns, and a positive relationship of IGFBP-2 with Interleukin (IL)-6. The role of cortisol in the fetus at birth is largely unknown, and interactions among peptides are their real effect on birth size is unknown. Furthermore, almost all studies have previously assayed peptides in serum several years after birth, and follow-up data from pregnancy are always lacking. This study aimed at establishing and clarifying the effect of cord serum insulin, IGF-II, IGFBP-2, cortisol and IL-6 concentrations on birth length and weight.
METHODS:
23 IUGR and 37 AGA subjects were followed up from the beginning of pregnancy, and were of comparable gestational age. Insulin, IGF-II, IGFBP-2, cortisol and IL-6 concentrations were assayed in cord serum at birth, and a multiple regression model was designed and applied to assess which were the significant biochemical determinants of birth size.
RESULTS:
Insulin, cortisol, and IL-6, showed similar concentrations in IUGR and AGA as previously described, whereas IGF-II was lower, and IGFBP-2 increased in IUGR compared with AGA. IGF-II serum concentration was found to have a significant positive effect on both birth length (r:(:)0.546; p: 0.001) and weight (r:0.679; p: 0.0001). IGFBP-2 had a near significant negative effect on both birth weight (r:-0.342; p: 0.05) and length (r:-0.372; p:0.03).
CONCLUSION:
IGF-II cord serum concentration was shown to have a significant positive effect on both birth length and weight, whereas IGFBP-2 had a significant negative effect. Insulin, cortisol, and IL-6 cord serum concentrations had no significant effect on birth size.
Direct interaction of ligand-receptor pairs specifying stomatal patterning.
Source
Department of Biology.
Abstract
Valves on the plant epidermis called stomata develop according to positional cues, which likely involve putative ligands (EPIDERMAL PATTERNING FACTORS [EPFs]) and putative receptors (ERECTA family receptor kinases and TOO MANY MOUTHS [TMM]) in Arabidopsis. Here we report the direct, robust, and saturable binding of bioactive EPFpeptides to the ERECTA family. In contrast, TMM exhibits negligible binding to EPF1 but binding to EPF2. The ERECTA family forms receptor homomers in vivo. On the other hand, TMM associates with the ERECTA family but not with itself. While ERECTA family receptor kinases exhibit complex redundancy, blocking ERECTA and ERECTA-LIKE1 (ERL1) signaling confers specific insensitivity to EPF2 and EPF1, respectively. Our results place the ERECTA family as the primary receptors for EPFs with TMM as a signal modulator and establish EPF2-ERECTA and EPF1-ERL1 as ligand-receptor pairs specifying two steps of stomatal development: initiation and spacing divisions.
Human Protein Arginine Methyltransferase 7 (PRMT7) is a Type III Enzyme Forming ω-NG-Monomethylated Arginine Residues.
Source
UCLA, United States.
Abstract
Full-length human protein arginine methyltransferase 7 (PRMT7) expressed as a fusion protein in Escherichia coli was initially found to generate only ω-N(G) monomethylated arginine residues in small peptides, suggesting that it is a type III enzyme. A later study, however, characterized fusion proteins of PRMT7 expressed in bacterial and mammalian cells as a type II/type I enzyme, capable of producing symmetrically dimethylated arginine (type II activity) as well as small amounts of asymmetric dimethylarginine (type I activity). We have sought to clarify the enzymatic activity of human PRMT7. We analyzed the in vitro methylation products of a glutathione-S-transferase (GST)-PRMT7 fusion protein with robust activity using a variety of arginine-containing synthetic peptides and protein substrates, including a GST-fusion with the N-terminal domain of fibrillarin (GST-GAR), myelin basic protein and recombinant human histones H2A, H2B, H3, and H4. Regardless of methylation reaction conditions (incubation time, reaction volume and substrate concentration), we found that PRMT7 only produces ω-N(G)-monomethylarginine with these substrates. In control experiments, we showed that mammalian GST-PRMT1 and Myc-PRMT5 were, unlike PRMT7, able to dimethylate both peptide P-SmD3 and SmB/D3 to give the expected asymmetric and symmetric products, respectively. These experiments show that PRMT7 is indeed a type III human methyltransferase capable of forming only ω-N(G)-monomethylarginine, not ADMA or SDMA, under the conditions tested.
Cell-penetrating properties of the transactivator of transcription and polyarginine (R9) peptides, their conjugative effect on nanoparticles and the prospect of conjugation with arsenic trioxide.
Source
aNanomedicine-Laboratory of Immunology and Molecular Biomedical Research (LIMBR), Centre for Biotechnology and Interdisciplinary Biosciences (BioDeakin), Institute for Technology and Research Innovation (ITRI), Geelong Technology Precinct (GTP), Deakin University, Geelong, Vic., Australia bNano-biotech Lab, Department of Zoology, K.M. College, University of Delhi, Delhi, India.
Abstract
Cell-penetrating peptides (CPPs) are short chains of amino acids with the distinct ability to cross cell plasma membranes. They are usually between seven and 30 residues in length. The mechanism of action is still a highly debated subject among researchers; it seems that a commonality between all CPPs is the presence of positively charged residues within the amino acid chain. Polyarginine and the transactivator of transcription peptide are two widely used CPPs. One distinct application of these CPPs is the ability to further enhance the therapeutic properties of a range of different agents. One group of agents of particular importance are nanoparticles (NPs). Most NPs have no mechanism for cellular uptake. Hence, by conjugating CPPs to NPs, the amount of NPs taken up by cells can be increased, and therefore, the therapeutic benefits can be maximized. Some examples of this will be explored further in this review. In addition to CPPs, the concept of conjugation with the anticancer drug arsenic trioxide is reviewed and the prospect of transactivator of transcription-conjugated arsenic trioxide albumin microspheres is also discussed. Recent locked nucleic acid technology to stabilize nucleotides (RNA or DNA) aptamer complexes able to target cancer cells more specifically and selectively to kill tumour cells and spare normal body cells. NPs tagged with modified locked nucleic acid-aptamers have the potential to kill cancer cells more specifically and effectively while sparing normal cells.
A fluorescent amino acid probe to monitor efficiency of peptide conjugation to glass surfaces for high density microarrays.
Source
Department of Bioengineering and Center for Bioengineering Research, Bourns College of Engineering, University of California at Riverside, 900 University Avenue, Riverside, CA 92521, USA. jiayu.liao@ucr.edu.
Abstract
Using a fluorescent NBD amino acid, new protease substrates were developed that are attractive because of the excellent chemical stability and long wavelength of excitation (480 nm) of the NBD fluorophore. The fluorescent peptidesare synthesized by Fmoc solid-phase peptide synthesis. An example peptide was efficiently immobilized onto a microarray surface using click chemistry, and its proteolysis was monitored by fluorescence imaging. Excellent site specificity was achieved for the protease. Fluorescent peptides are also used to monitor the conjugation efficiency onto a surface using a standard microarray scanner.
Innate immunity in the small intestine.
Source
Division of Gastroenterology, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA.
Abstract
PURPOSE OF REVIEW:
This article reviews the most recent publications on innate immunity in the small intestine. We will go over the innate immune receptors that act as sensors of microbial presence or cell injury, Paneth cells as the main epithelial cell type that secrete antimicrobial peptides, and mucosal production of immunoglobulin A (IgA). In addition, we will give an update on examples of imbalance of the innate immune response resulting in clinical disease with the most relevant example being Crohn's disease.
RECENT FINDINGS:
Toll-like receptors (TLRs) are involved in B-cell homing to the intestine, rejection of small intestinal allografts, and recruitment of mast cells. The TLR adaptor Toll/interleukin-1 receptor domain-containing adapter-inducing interferon-β is necessary to activate innate immunity after Yersinia enterocolitica infection. Moreover, MyD88 is required to keep the intestinal microbiota under control and physically separated from the epithelium, and RegIIIγ is responsible for the bacterial segregation from the lining epithelial cells. In Crohn's disease, ATG16L1 T300A variant promotes a proinflammatory response; and miR-196 downregulates a protective immunity-related GTPase family M protein (IRGM) polymorphism leading to impaired clearance of adherent Escherichia coli in the intestine.
SUMMARY:
The intestine is continuously exposed to dietary and microbial antigens. The host has to maintain intestinal homeostasis to keep the commensal and pathogenic bacteria under control. Some of the mechanisms to do so are by expression of innate immune receptors, production of antimicrobial peptides, secretion of IgA, or autophagy of intracellular bacteria. Unfortunately, in some cases the innate immune response fails to protect the host and chronic inflammation, transplant rejection, or other disorders may occur.
Plasma Adrenomedullin Concentration in Dogs with Myxomatous Mitral Valvular Disease.
Source
Laboratory of Veterinary Surgery, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University.
Abstract
Adrenomedullin (AM), a peptide identified to have vasodilating and natriuretic effects, is involved in the regulation of the cardiovascular system. To evaluate plasma AM concentration in dogs with myxomatous mitral valvular disease (MMVD), and to investigate the associations between the concentrations of plasma AM and natriuretic peptides and the echocardiographic data, we evaluated plasma AM concentrations in 31 healthy control dogs and 57 dogs with MMVD. Plasma AM concentrations in dogs with MMVD were higher than that in the control subjects. Plasma AM concentration increased in population to the severity of heart failure according to the International Small Animal Cardiac Health Council (ISACHC). AM concentrations were respectively 25.1 ± 5.0 fmol/ml (ISACHC class Ia), 29.9 ± 11.0 fmol/ml (ISACHC class Ib), 43.4 ± 19.8 fmol/ml (ISACHC class II) and 73.5 ± 21.7 fmol/ml (ISACHC class III) and 7.5 ± 5.1 fmol/ml (control group). The response-operating characteristics (ROC) curve indicated an area of 0.93 (95% CI, 0.8801-0.9889; < 0.0001), a cutoff value of 30.5 fmol/ml, a sensitivity of 87.1 %, and a specificity of 82.5 % for the determination of congestive heart failure. Plasma AM concentrations correlated with atrial natriuretic peptide concentrations, LA/Ao ratio, and left ventricular diameter. In conclusion, AM may be potential diagnostic marker for canine MMVD and possibly plays a pathophysiological role in collaboration with the other neurohumoral factors such as natriuretic peptides.
Apelin supports primary rat retinal Müller cells under chemical hypoxia and glucose deprivation.
Source
Department of Ophthalmology, People's Hospital, Peking University, & Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100044, China.
Abstract
Müller cells support the integrity of the blood-retinal barrier, whereas their dysfunction under pathological conditions may contribute to retinal edema formation. The apelin peptide, as the endogenous ligand of G protein-coupled receptor APJ, participates in numbers of physiological and pathological processes. Recent studies highlight its emerging role against ischemic injury. Our study aimed to investigate the potential neuroprotection of apelin for primary rat retinal Müller cells under hypoxia or glucose-deprivation (GD) by cell viability, migration and apoptosis, as well as apelin/APJ immunofluorescence labeling and mRNA expression. The results showed that exogenous apelin significantly stimulated Müller cells viability and migration under normal, hypoxic and glucose-free condition, also prevented apoptosis. Apelin immunoreactivities represented weak and diffuse staining in the cytoplasm, along with restricted nuclear APJ expression. They both appeared stronger immunoreactivities after 12h hypoxia. Under hypoxic stress, apelin mRNA expression began to increase at 6h (9.97 folds, p<0.01), and APJ mRNA also up-regulated (2h 6.50 folds, p<0.05; 4h 2.25 folds, p<0.05; 6h 14 folds, p<0.01), whereas they both down-regulated during 4-12h GD. Our results suggested that apelin induced the tolerance of Müller cells to hypoxia and GD. Its administration might be a promising protection for blood-retinal barrier to ischemia.
Copyright © 2011. Published by Elsevier Inc.
Glycosylations and truncations of functional cereal phytases expressed and secreted by Pichia pastoris documented by mass spectrometry.
Source
Faculty of Science and Technology, Dept. of Molecular Biology and Genetics, Aarhus University, Research Centre Flakkebjerg, DK-4200 Slagelse, Denmark.
Abstract
Cereal purple acid phosphatase-type phytases, PAPhy, play an essential role in making phosphate accessible to mammalian digestion and reducing the environmental impact of manure. Studying the potential of PAPhy requires easy access to the enzymes. For that purpose wheat and barley isophytases have been expressed in Pichia pastoris from constructs encoding the alpha-mating factor at the N-termini and a His(6) tag before the stop codon in all constructs. A protein chemical study of a C-terminally truncated recombinant wheat phytase, r-TaPAPhy_b2, was carried out to clarifying the posttranslational processing of proteins secreted from P. pastoris. Extensive mass spectrometric sequencing of tryptic, chymotryptic and AspN derived peptides of both the native and endoH deglycosylated forms showed: (i) All mating factor derived sequence had been removed and further unspecific proteolysis left highly heterogeneous N-terminal variant forms of r-TaPAPhy; (ii) The His(6) tag had been retained or slightly truncated; (iii) All seven potential N-glycan sites were glycosylated except for two sites which were partially glycosylated by ca. 90% and 30%; (iv) Among the nine cysteine residues of this phytase, the most N-terminal residue is free, whereas the remaining eight appear to be disulfide bonded. It is noteworthy that already the first step in ESI-MS/MS sequencing had fragmented the hyper glycosylated peptides into free Z, Y and X mass spectrometric glycan fragments attached to the peptide.
Copyright © 2011 Elsevier Inc. All rights reserved.
Influence of stearyl and trifluoromethylquinoline modifications of the cell penetrating peptide TP10 on its interaction with a lipid membrane.
Source
Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1000 Ljubljana, Slovenia.
Abstract
The PepFect family of cell-penetrating peptides (CPPs) was designed to improve the delivery of nucleic acids across plasma membranes. We present here a comparative study of two members of the family, PepFect3 (PF3) and PepFect6 (PF6), together with their parental CPP transportan-10 (TP10), and their interactions with lipid membranes. We show that the addition of a stearyl moiety to TP10 increases the amphipathicity of these molecules and their ability to insert into a lipid monolayer composed of zwitterionic phospholipids. The addition of negatively charged phospholipids into the monolayer results in decreased binding and insertion of the stearylated peptides, indicating modification in the balance of hydrophobic versus electrostatic interactions of peptides with lipid bilayer, thus revealing some clues for the selective interaction of these CPPs with different lipids. The trifluoromethylquinoline moieties, in PF6 make no significant contribution to membrane binding and insertion. TP10 actively introduces pores into the bilayers of large and giant unilamellar vesicles, while PF3 and PF6 do so only at higher concentrations. This is consistent with the lower toxicity of PF3 and PF6 observed in previous studies.
Copyright © 2011. Published by Elsevier B.V.
A novel study on amyloid beta peptide 40, 42 and 40/42 ratio in Saudi autistics.
Abstract
ABSTRACT: Objectives: We examined whether plasma concentrations of amyloid beta (Abeta) as protein derivatives play a central role in the etiology of autistic features. Design and Methods: Concentrations of human Abeta (1-42), Abeta (1-40), and Abeta (40/42) in the plasma of 52 autistic children (aged 3-16 years) and 36 age-matched control subjects were determined by using the ELISA technique and were compared. Results: Compared to control subjects, autistic children exhibited significantly lower concentrations of both Abeta (1-40) and Abeta (1-42) and lower Abeta (40/42) concentration ratio. Receiver operating characteristics curve (ROC) analysis showed that these measurements of Abeta peptides showed high specificity and sensitivity in distinguishing autistic children from control subjects. Conclusions: Lower concentrations of Abeta (1-42) and Abeta (1-40) were attributed to loss of Abeta equilibrium between the brain and blood, an imbalance that may lead to failure to draw Abeta from the brain and/or impairment of beta- and gamma- secretase's concentration or kinetics as enzymes involving in Abeta production.
Photodissociation pathways and lifetimes of protonated peptides and their dimers.
Source
Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, DenmarkChemistry Department, Moscow State University, Moscow 119991, Russia and Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, DenmarkUniversité de Lyon, F-69622, Lyon, France and Université Lyon 1, Villeurbanne, CNRS, UMR 5579, LASIM, FranceUniversité de Lyon, F-69622, Lyon, France and Université Lyon 1, Villeurbanne, CNRS, UMR 5180, Sciences Analytiques, France.
Abstract
Photodissociation lifetimes and fragment channels of gas-phase, protonated YA(n) (n = 1,2) peptides and their dimers were measured with 266 nm photons. The protonated monomers were found to have a fast dissociation channel with an exponential lifetime of ∼200 ns while the protonated dimers show an additional slow dissociation component with a lifetime of ∼2 μs. Laser power dependence measurements enabled us to ascribe the fast channel in the monomer and the slow channel in the dimer to a one-photon process, whereas the fast dimer channel is from a two-photon process. The slow (1 photon) dissociation channel in the dimer was found to result in cleavage of the H-bonds after energy transfer through these H-bonds. In general, the dissociation of these protonated peptides is non-prompt and the decay time was found to increase with the size of the peptides. Quantum RRKM calculations of the microcanonical rate constants also confirmed a statistical nature of the photodissociation processes in the dipeptide monomers and dimers. The classical RRKM expression gives a rate constant as an analytical function of the number of active vibrational modes in the system, estimated separately on the basis of the equipartition theorem. It demonstrates encouraging results in predicting fragmentation lifetimes of protonated peptides. Finally, we present the first experimental evidence for a photo-induced conversion of tyrosine-containing peptides into monocyclic aromatic hydrocarbon along with a formamide molecule both found in space.
- PMID:
- 22239781
- [PubMed - in process]
Enhanced Separation and Characterization of Deamidated Peptides with RP-ERLIC-based Multidimensional Chromatography Coupled with Tandem Mass Spectrometry.
Abstract
Deamidation of asparaginyl residues in proteins produces a mixture of asparaginyl, n-aspartyl and isoaspartyl residues, which affects the proteins' structure, function and stability. Thus, it is important to identify and quantify the products to evaluate the effects in biological systems. It is still a challenging task to distinguish between the n-Asp and isoAsp deamidation products in a proteome-wide analysis due to their similar physicochemical properties. The quantification of the isomeric deamidated peptides is also rather difficult due to their coelution/poor separation in reverse-phase liquid chromatography (RPLC). We here propose a RP-ERLIC-MS/MS approach for separating and quantifying on a proteome-wide scale the three products related to deamidation of the same peptide. The key to the method is the use of RPLC in the first dimensional separation and ERLIC (electrostatic repulsion-hydrophilic interaction chromatography) in the second, with direct online coupling to tandem MS. The coelution of the three deamidation-related peptides in RPLC is then an asset, as they are collected in the same fraction. They are then separated and identified in the second dimension with ERLIC, which separates peptides based on both pI and GRAVY values. The coelution of the three products in RPLC and their efficient separation in ERLIC were validated using synthetic peptides, and the performance of ERLIC-MS/MS was tested using peptide mixtures from two proteins. Applying this sequence to rat liver tissue, we identified 302 unique N-deamidated peptides, of which 20 were identified via all three deamidation-related products and 70 of which were identified via two of them.
Semi-Automated Identification of N-Glycopeptides by Hydrophilic Interaction Chromatography, nano-Reverse-Phase LC-MS/MS, and Glycan Database Search.
Abstract
Glycoproteins fulfill many indispensable biological functions and changes in protein glycosylation have been observed in various diseases. Improved analytical methods are needed to allow a complete characterization of this complex and common posttranslational modification. In this study, we present a workflow for the analysis of the microheterogeneity of N-glycoproteins which couples hydrophilic interaction and nano-reverse-phase C18 chromatography to tandem QTOF mass spectrometric analysis. A glycan database search program, GlycoPeptideSearch, was developed to match N-glycopeptide MS/MS spectra with the glycopeptides comprised of a glycan drawn from the GlycomeDB glycan structure database and a peptide from a user-specified set of potentially glycosylated peptides. Application of the workflow to human haptoglobin and hemopexin, two microheterogeneous N-glycoproteins, identified a total of 57 distinct site-specific glycoforms in the case of haptoglobin and 14 site-specific glycoforms of hemopexin. Using glycan oxonium ions, peptide-characteristic glycopeptide fragment ions, and by collapsing topologically redundant glycans, the search software was able to make unique N-glycopeptide assignments for 51% of assigned spectra, with the remaining assignments primarily representing isobaric topological rearrangements. The optimized workflow, coupled with GlycoPeptideSearch, is expected to make high-throughput semi-automated glycopeptide identification feasible for a wide range of users.
Specific Material Recognition by Small Peptides Mediated by the Interfacial Solvent Structure.
Abstract
We present evidence that specific material recognition by small peptides is governed by local solvent density variations at solid/liquid interfaces, sensed by the side-chain residues with atomic-scale precision. In particular, we unveil the origin of the selectivity of the binding motif RKLPDA for Ti over Si using a combination of Metadynamics and Steered Molecular Dynamics simulations, obtaining adsorption free energies and adhesion forces in quantitative agreement with corresponding experiments. For an accurate description we employ realistic models of the natively oxidized surfaces which go beyond the commonly used perfect crystal surfaces. These results have profound implications for nanotechnology and materials science applications, offering a previously missing structure-function relationship for the rational design of materials-selective peptide sequences.
Using Extracellular Matrix-Derived Peptides to Alter the Microenvironment for Myocardial Repair.
Source
University of California San Francisco, Box 1354, San Francisco, CA 94143, USA. lee@medicine.ucsf.edu.
Abstract
Myocardial repair remains a major challenge for both cellular and tissue engineering approaches. Several studies have been conducted looking at utilizing extracellular matrix-based therapies to promote repair after a myocardial infarction. In this review, strategies for treating myocardial infarctions using extracellular matrix-derived peptides are discussed. Using an ischemia/reperfusion myocardial infarction rodent model, we showed that extracellular-matrix-derived peptides were able to induce angiogenesis and alter the negative remodeling seen after a myocardial infarction. This therapy opens up a potentially new non-invasive strategy for repairing damaged cardiac tissue.
- PMID:
- 22239636
- [PubMed - as supplied by publisher]
Hybrid compounds: from simple combinations to nanomachines.
Source
Department of Neuropathology, Heinrich Heine University Dsseldorf, Dsseldorf, Germany.
Abstract
The combination of two different and independently acting compounds into one covalently linked hybrid compound can convey synergy from the effects of both independently acting moieties to the new composite compound, leading to a pharmacological potency greater than the sum of each individual moiety's potencies. Here, we review a variety of such hybrid compounds, which can consist of various functional parts, molecular recognition or subcellular targeting moieties, or combinations thereof, acting either simultaneously or sequentially. Such moieties within a hybrid compound can consist of a variety of substance classes, including small organic molecules, polypeptides or nucleic acids identified either via rational molecular design or selection from libraries. Precedent for hybrid compounds comes from naturally occurring proteins and small molecules, such as botulinum toxin and bleomycin, which are secreted by micro-organisms. We review the high degree of suitability of hybrid compounds for the treatment of multifactorial diseases by simultaneously hitting several targets along an identified disease pathway. Examples are hybrid compounds against Alzheimer's disease, against the cancer-relevant phosphoinisitide-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and epidermal growth factor signaling cascade, or in antimalarial therapy via simultaneous hitting of different mechanisms of hemozoin formation. Molecular recognition by peptides or aptamers (recognition-specific RNA or peptide sequences) can be combined with the transport of small molecule β-sheet breakers or toxins, or targeting to ubiquitin-dependent proteolysis. The vision of molecular nanomachines is currently realized in sequentially acting modular nanotransporters, consisting of four modules including a target, a membrane and nuclear translocation sequence, as well as a drug attachment domain. Through the rational combination of existing drugs and the synergy of their effects, a rapid amplification of their potency may be achieved, greatly accelerating drug development. A further enhancement of simultaneous multitarget action is enabled through the design of multifunctional hybrid drugs with sequential effects that make these hybrid molecules resemble intelligent nanomachines.
Computed and Experimental Chemical Shift Parameters for Rigid and Flexible YAF Peptides in the Solid State.
Abstract
DFT methods were employed to compute the 13C NMR chemical shift tensor (CST) parameters for crystals of YAFpeptides (Tyr-Ala-Phe) with different stereochemistry for the Ala residue. Tyr-D-Ala-Phe 1 crystallizes in the C2 space group while Tyr- L-Ala-Phe crystallizes in either the P21212 space group (2a) or the P65 space group (2b). PISEMA MAS measurements for samples with a natural abundance of 1H and 13C nuclei and 2H QUADECHO experiments for samples with deuterium labeled aromatic rings were used to analyze the geometry and time scale of the molecular motion. At ambient temperature, the tyrosine ring of sample 1 is rigid and the phenylalanine ring undergoes a pi-jump, both rings in sample 2a are static, and both rings in sample 2b undergo a fast regime exchange. The theoretical values of the CST were obtained for isolated molecules (IM) and clusters employing the ONIOM approach. The experimental 13C delta(ii) parameters for all of the samples were measured via a 2D PASS sequence. Significant scatter of the computed versus the experimental 13C CST parameters was observed for 1 and 2b, while the observed correlation was very good for 2a. In this report, we show that the quality of the 13C delta(ii)/13C sigma(ii) correlations, when properly interpreted, can be a source of important information about local molecular motions.
Peptide-mediated nanoengineering of inorganic particle sur-faces: A general route toward surface functionalization via peptide adhesion domains.
Abstract
The present paper reports on a generic strategy to specifically introduce functionalities or functions to surfaces of inorganic nanoparticles by exploiting tailor-made peptide-adhesion domains. Suitable peptide sequences could be selected for specific inorganic particles by biocombinatorial means of phage display. The selected peptides exhibit sequence-specific adhesion onto the particle surfaces and therefore allowed non-covalent surface decoration with e. g. fluorescence labels or poly(ethylene oxide). This proves to result in very stable surface modifications as shown by the high resistance of the coatings against washing. Moreover, the PEO-coating dramatically reduces protein adsorption to the particles by 80%, as compared to non-functionalized particles. The peptide-mediated functionalization of inorganic particle surfaces was demonstrated on gadolinium oxide particles. However, the specific and non-covalent modification of inorganic particle surfaces represents a generic strategy to nanoengineering of surfaces of nano- or micro particles as well as planar materials surfaces.
Oligovalent Amyloid-Binding Agents Reduce SEVI-Mediated Enhancement of HIV-1 Infection.
Source
Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093-0358, United States.
Abstract
This paper evaluates the use of oligovalent amyloid-binding molecules as potential agents that can reduce the enhancement of human immunodeficiency virus-1 (HIV-1) infection in cells by semen-derived enhancer of virus infection (SEVI) fibrils. These naturally occurring amyloid fibrils found in semen have been implicated as mediators that can facilitate the attachment and internalization of HIV-1 virions to immune cells. Molecules that are capable of reducing the role of SEVI in HIV-1 infection may, therefore, represent a novel strategy to reduce the rate of sexual transmission of HIV-1 in humans. Here, we evaluated a set of synthetic, oligovalent derivatives of benzothiazole aniline (BTA, a known amyloid-binding molecule) for their capability to bind cooperatively to aggregated amyloid peptides and to neutralize the effects of SEVI in HIV-1 infection. We demonstrate that these BTA derivatives exhibit a general trend of increased binding to aggregated amyloids as a function of increasing valence number of the oligomer. Importantly, we find that oligomers of BTA show improved capability to reduce SEVI-mediated infection of HIV-1 in cells compared to a BTA monomer, with the pentamer exhibiting a 65-fold improvement in efficacy compared to a previously reported monomeric BTA derivative. These results, thus, support the use of amyloid-targeting molecules as potential supplements for microbicides to curb the spread of HIV-1 through sexual contact.
No comments:
Post a Comment