共查询到20条相似文献,搜索用时 31 毫秒
1.
Synthesis and characterization of a flexible crosslinked polystyrene graftedpolyethyleneglycol (PEG) resin which allows for efficient synthesis of aggregating peptides in high yield and purity has been described. The resin showed rigidity, mechanical and chemical stability, and improved swelling and solvation characteristics essential for the successful synthesis of peptides. To demonstrate the usefulness of the new resin in polypeptide synthesis, a 4-(hydroxymethyl)phenoxyacetic acid (HMPA) handle was anchored to the free terminus of PEG and a typical hydrophobic peptide, Alzheimer's -amyloid plaque protein (33–42) fragment, was synthesized using Fmoc/t-Bu tactics. The new resin was compared with commercially available 1 mol% divinylbenzene (DVB)-crosslinked Tentagel resin under identical conditions. HPLC profiles and LC/MS analyses of the crude products revealed the high synthetic efficiency of the newly developed support. Efficiency of the resin was further illustrated by the gel-phase synthesis of a 15-residue peptide, (28–42) fragment of -amyloid protein. 相似文献
2.
Ajikumar P. K. Devaky K. S. 《International journal of peptide research and therapeutics》2000,7(4):207-215
Summary Studies leading to optimization of butanediol dimethacrylate-crosslinked polystyrene supports (BDDMA-PS) for solid phase peptide
synthesis are delineated. BDDMA-PS copolymers with different crosslink densities were prepared and functionalised with chloromethyl
groups. The reactivity of the Lys(2-Cl−Z)−OH residue bound to these polymers through a benzyl ester linkage was investigated
by following the kinetics of acylation by the HOBt active ester of Boc-Alanine. From the results it was observed that the
rate of peptide bond formation was maximum for a 2% BDDMA crosslinked resin. This resin was compared with a 2% DVB-crosslinked
polystyrene resin (DVB-PS). Synthesis of an extremely insoluble, hydrophobic, antiparallel β-sheeted difficult sequence peptide
LMVGGVVIA (β 34–42), C-terminal fragment of β-amyloid protein, β (1–42), was carried out on both 2% DVB-PS and 2% BDDMA-crosslinked
polystyrene supports. The synthesis of the peptide was carried out using Boc amino acid strategy. Greater extent of swelling
of the resino peptide, increased coupling efficiency during the assembly of amino acids and relatively high purity of synthesised
peptide were observed in the case of 2% BDDMA-PS polymer. 相似文献
3.
Frankiewicz Lukasz P. Pulka Karolina Lipkowski Andrzej W. Misicka Aleksandra 《International journal of peptide research and therapeutics》2002,9(2-3):77-81
Summary This article presents kinetic studies of cross interaction of β-amyloid peptide and prion protein fragments. Syntheses of
three peptides (β25-35, β22-35 and PrP 109–126) were performed. Those peptides were used for aggregation studies in PBS and
TRIS buffers using HPLC with DAD detector. Comparison of aggregation of peptides alone and in combination with other fragments
was investigated. In all cases aggregation was faster in PBS than in TRIS solution. Obtained results suggest that β-amyloid
peptide and prion protein may interact to form macromolecular complexes with different ability for aggregation. 相似文献
4.
Gehman JD O'Brien CC Shabanpoor F Wade JD Separovic F 《European biophysics journal : EBJ》2008,37(3):333-344
Aβ(1–42) peptide, found as aggregated species in Alzheimer’s disease brain, is linked to the onset of dementia. We detail
results of 31P and 2H solid-state NMR studies of model membranes with Aβ peptides and the effect of metal ions (Cu2+ and Zn2+), which are found concentrated in amyloid plaques. The effects on the lipid bilayer and the peptide structure are different
for membrane incorporated or associated peptides. Copper ions alone destabilise the lipid bilayer and induce formation of
smaller vesicles, but not when Aβ(1–42) is associated with the bilayer membrane. Aβ(25–35), a fragment from the C-terminal
end of Aβ(1–42), which lacks the metal coordinating sites found in the full length peptide, is neurotoxic to cortical cortex
cell cultures. Addition of metal ions has little effect on membrane bilayers with Aβ(25–35) peptides. 31P magic angle spinning NMR data show that Aβ(1–42) and Aβ(1–42)-Cu2+ complexes interact at the surface of anionic phospholipid membranes. Incorporated peptides, however, appear to disrupt the
membrane more severely than associated peptides. Solid-state 13C NMR was used to compare structural changes of Aβ(1–42) to those of Aβ(25–35) in model membrane systems of anionic phospholipids
and cholesterol. The Aβ peptides appeared to have an increase in β-strand structure at the C-terminus when added to phospholipid
liposomes. The inclusion of Cu2+ also influenced the observed chemical shift of residues from the C-terminal half, providing structural clues for the lipid-associated
Aβ/metal complex. The results point to the complex pathway(s) for toxicity of the full-length peptide.
Australian Society for Biophysics Special Issue: Metals and Membranes in Neuroscience. 相似文献
5.
Christian J. Pike rea J. Walencewicz-Wasserman Joseph Kosmoski David H. Cribbs Charles G. Glabe Carl W. Cotman 《Journal of neurochemistry》1995,64(1):253-265
Abstract: The neurodegeneration of Alzheimer's disease has been theorized to be mediated, at least in part, by insoluble aggregates of β-amyloid protein that are widely distributed in the form of plaques throughout brain regions affected by the disease. Previous studies by our laboratory and others have demonstrated that the neurotoxicity of β-amyloid in vitro is dependent upon its spontaneous adoption of an aggregated structure. In this study, we report extensive structure-activity analyses of a series of peptides derived from both the proposed active fragment of β-amyloid, β25–35, and the full-length protein, β1–42. We examine the effects of amino acid residue deletions and substitutions on the ability of β-amyloid peptides to both form sedimentable aggregates and induce toxicity in cultured hippocampal neurons. We observe that significant levels of peptide aggregation are always associated with significant β-amyloid-induced neurotoxicity. Further, both N- and C-terminal regions of β25–35 appear to contribute to these processes. In particular, significant disruption of peptide aggregation and toxicity result from alterations in the β33–35 region. In β1–42 peptides, aggregation disruption is evidenced by changes in both electrophoresis profiles and fibril morphology visualized at the light and electron microscope levels. Using circular dichroism analysis in a subset of peptides, we observed classic features of β-sheet secondary structure in aggregating, toxic β-amyloid peptides but not in nonaggregating, nontoxic β-amyloid peptides. Together, these data further define the primary and secondary structures of β-amyloid that are involved in its in vitro assembly into neurotoxic peptide aggregates and may underlie both its pathological deposition and subsequent degenerative effects in Alzheimer's disease. 相似文献
6.
Studies leading to optimization of butanedioldimethacrylate-crosslinked polystyrene supports (BDDMA–PS) forsolid phase peptide synthesis are delineated. BDDMA–PScopolymers with different crosslink densities were prepared andfunctionalised with chloromethyl groups. The reactivity of theLys(2-Cl-Z)-OH residue bound to these polymers through a benzylester linkage was investigated by following the kinetics ofacylation by the HOBt active ester of Boc-Alanine. From theresults it was observed that the rate of peptide bond formationwas maximum for a 2% BDDMA crosslinked resin. This resin wascompared with a 2% DVB-crosslinked polystyrene resin (DVB–PS). Synthesis of an extremely insoluble, hydrophobic,antiparallel -sheeted difficult sequencepeptide LMVGGVVIA ( 34–42), C-terminal fragment of -amyloid protein, (1–42), wascarried out on both 2% DVB–PS and 2% BDDMA-crosslinkedpolystyrene supports. The synthesis of the peptide was carriedout using Boc amino acid strategy. Greater extent of swellingof the resino peptide, increased coupling efficiency during theassembly of amino acids and relatively high purity of synthesised peptide were observed in the case of 2% BDDMA–PS polymer. 相似文献
7.
Stephen D. Skaper Nicholas A. Evans Peter E. Soden Claudia Rosin Laura Facci Jill C. Richardson 《Neurochemical research》2009,34(12):2243-2250
Alzheimer’s disease is characterised by regional neuronal degeneration, synaptic loss, and the progressive deposition of the
4 kDa β-amyloid peptide (Aβ) in senile plaques and accumulation of tau protein as neurofibrillary tangles. Aβ derives from
the larger precursor molecule, amyloid precursor protein (APP) by proteolytic processing via β- and γ-secretases. While APP
expression is well documented in neurons and astrocytes, the case for oligodendrocytes is less clear. The latter cell type
is reported to express different isoforms of APP, and we have confirmed this observation by immunocytochemistry in cultures
of differentiated rat cortical oligodendrocytes. Moreover, by means of a sensitive electrochemiluminescent immunoassay employing
Aβ C-terminal specific antibodies, mature oligodendrocytes are shown to secrete the 40 and 42 amino acid Aβ species (Aβ40
and Aβ42). Secretion of Aβ peptides was reduced by incubating oligodendrocytes with α- and β-secretase inhibitors, or a γ-secretase
inhibitor. Disturbances of APP processing and/or synthesis in oligodendrocytes may account for some myelin disorders observed
in Alzheimer’s disease and other senile dementias. 相似文献
8.
Krishnakumar I. M. Mathew Beena 《International journal of peptide research and therapeutics》2000,7(6):317-323
Summary The synthetic usefulness of the protocol using NMP/DMSO and DIEA for the synthesis of difficult sequence peptides on amphiphilic
and flexible 1,4-butanediol dimethacrylate-crosslinked polystyrene (BDDMA-PS) support was demonstrated by synthesizing [DAla17] analogue of gonadotropin releasing hormone precursor protein fragment (14–36) [hGnRH (14–36)] using Boc chemistry. The swelling
capacity of the peptidyl resin was followed as a measure of the aggregation of pendant peptide chains on the support. The
progress of chain assembly was monitored by quantitative ninhydrin test and amino acid analysis. The purity of the peptide
was checked by reverse phase HPLC and characterized by amino acid analysis and electrospray ionisation mass spectrometry (ESI-MS). 相似文献
9.
Inui Tatsuya Bódi József Nishio Hideki Nishiuchi Yuji Kimura Terutoshi 《International journal of peptide research and therapeutics》2001,8(6):319-330
Summary Segment condensation reaction of sparingly soluble protected peptides proceeded smoothly in CHCl3-phenol mixed solvent without danger of epimerization or of significant ester formation with the carboxyl component when 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide
(EDC) was employed in the presence of 3,4-dihydro-3-hydroxy-4-oxo-1,2,3-benzotriazine (HOOBt). The optimal conditions for
enhancement of peptide coupling mediated by EDC/HOOBt in CHCl3-phenol were determined and successfully applied to the synthesis of amyloid β-peptide (1–42), (1–43) and [Pyr3]-(3–42). These peptides of high homogeneity were used to examine the relation between structure and amyloidogenesis by means
of CD spectra and fluorimetric assay. 相似文献
10.
(1) Huperzine A, a promising therapeutic agent for Alzheimer’s disease (AD), was tested for its effects on cholinergic and
monoaminergic dysfunction induced by injecting β-amyloid peptide-(1–40) into nucleus basalis magnocellularis of the rat. (2)
Bilateral injection of 10 μg β-amyloid peptide-(1–40) into nucleus basalis magnocellularis produced local deposits of amyloid
plaque and functional abnormalities detected by microdialysis. In medial prefrontal cortex, reductions in the basal levels
and stimulated release of acetylcholine, dopamine, norepinephrine, and 5-hydroxytryptamine were observed. However, oral huperzine
A (0.18 mg/kg, once daily for 21 consecutive days) markedly reduced morphologic abnormalities at the injection site in rats
infused with β-amyloid peptide-(1–40). Likewise, this treatment ameliorated the β-amyloid peptide-(1–40)-induced deficits
in extracellular acetylcholine, dopamine, and norepinephrine (though not 5-hydroxytryptamine) in medial prefrontal cortex,
and lessened the reduction in nicotine or methoctramine-stimulated release of acetylcholine and K+-evoked releases of acetylcholine and dopamine. (3) The present results provide the first direct evidence that huperzine A
acts to oppose neurotoxic effects of β-amyloid peptide on cholinergic, dopaminergic, and noradrenergic systems of the rat
forebrain. 相似文献
11.
The main component of senile plaques found in AD brain is amyloid β-peptide (Aβ), and the neurotoxicity and aggregation of
Aβ are associated with the formation of β-sheet structure. Experimentally, beta sheet breaker (BSB) peptide fragment Leu-Pro-Phe-Phe-Asp
(LPFFD) can combine with Aβ, which can inhibit the aggregation of Aβ. In order to explore why LPFFD can inhibit the formation
of β-sheet conformation of Aβ at atomic level, first, molecular docking is performed to obtain the binding sites of LPFFD
on the Aβ(1–42) (LPFFD/Aβ(1–42)), which is taken as the initial conformation for MD simulations. Then, MD simulations on LPFFD/Aβ(1–42)
in water are carried out. The results demonstrate that LPFFD can inhibit the conformational transition from α-helix to β-sheet
structure for the C-terminus of Aβ(1–42), which may be attributed to the hydrophobicity decreasing of C-terminus residues
of Aβ(1–42) and formation probability decreasing of the salt bridge Asp23-Lys28 in the presence of LPFFD. 相似文献
12.
Proteins have been considered to consist exclusively of l-amino acids in living tissues. However, our previous studies showed that two specific aspartyl (Asp) residues in αA- and
αB-crystallins from human eye lenses invert to the d-isomers to a high degree during aging. The reaction is also accompanied by isomerization into a form containing β-Asp (isoaspartate)
residues. The appearance of d- and β-Asp in a protein potentially induces large changes to the higher order structure of the protein as well as to its
function. However, it remains unclear whether the formation of the Asp isomer is the direct trigger of the change to the higher
order structure and function. In this study, in order to clarify the effect of the inversion to d-isomers in a protein, we synthesized peptides corresponding to the 70–88 (KFVIFLDVKHFSPEDLTVK) fragment of human αA-crystallin
and its corresponding diastereoisomers in which lα-Asp was replaced with lβ-Asp, dα-Asp, and dβ-Asp at position 76 and compared their biochemical properties with that of normal peptide. The peptides containing abnormal
isomers (lβ-Asp, dα-Asp, and dβ-Asp residues, respectively) were more hydrophilic than the normal peptide (containing lα-Asp), lost β-sheet structure and changed to random structures. The normal peptide promoted the aggregation of insulin while
the other three isomers suppressed the aggregation of insulin. This is the first evidence that a single substitution of an
Asp isomer in a peptide induces a large change to the properties of the peptide. 相似文献
13.
Tau hyperphosphorylation, amyloid plaques, and neuronal death are major neuropathological features of Alzheimer’s disease
(AD) and Prion-related encephalopathies (PRE). Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase, active in post-mitotic
neurons, where it regulates survival and death pathways. Overactivation of Cdk5 is conferred by p25, a truncated fragment
of the p35 activator formed upon calpain activation. Cdk5 deregulation causes abnormal phosphorylation of microtubule-associated
protein tau, leading to neurodegeneration. In this work we investigated the involvement of Cdk5 in the neurodegeneration triggered
by amyloid-beta (Aβ) and prion (PrP) peptides, the culprit agents of AD and PRE. As a work model, we used cultured rat cortical
neurons treated with Aβ1–40 and PrP106–126 synthetic peptides. The obtained data show that apoptotic neuronal death caused by both the peptides was in part due to Cdk5
deregulation. After peptide treatment, p25 levels were significantly enhanced in a pattern consistent with the augment in
calpain activity. Moreover, Aβ1–40 and PrP106–126 increased the levels of tau protein phosphorylated at Ser202/Thr205. Cdk5 (roscovitine) and calpain (MDL28170) inhibitors
reverted tau hyperphosphorylation and prevented neuronal death caused by Aβ1–40 and PrP106–126. This study demonstrates, for the first time, that Cdk5 is involved in PrP-neurotoxicity. Altogether, our data suggests that
Cdk5 plays an active role in the pathogenesis of AD and PRE. 相似文献
14.
Lambracht-Washington D Qu BX Fu M Anderson LD Stüve O Eagar TN Rosenberg RN 《Cellular and molecular neurobiology》2011,31(6):867-874
The pathogenesis of Alzheimer’s disease (AD) has been strongly associated with the accumulation of amyloid beta (Aβ) peptides
in brain, and immunotherapy targeting Aβ provides potential for AD prevention. A clinical trial in which AD patients were
immunized with Aβ42 peptide was stopped when 6% of participants showed meningoencephalitis, apparently due to an inflammatory
Th1 immune response. Previously, we and other have shown that Aβ42 DNA vaccination via gene gun generates a Th2 cellular immune
response, which was shown by analyses of the respective antibody isotype profiles. We also determined that in vitro T cell
proliferation in response to Aβ42 peptide re-stimulation was absent in DNA Aβ42 trimer-immunized mice when compared to Aβ42
peptide-immunized mice. To further characterize this observation prospectively and longitudinally, we analyzed the immune
response in wild-type mice after vaccination with Aβ42 trimer DNA and Aβ42 peptide with Quil A adjuvant. Wild-type mice were
immunized with short-term (1–3× vaccinations) or long-term (6× vacinations) immunization strategies. Antibody titers and isotype
profiles of the Aβ42 specific antibodies, as well as cytokine profiles and cell proliferation studies from this longitudinal
study were determined. Sufficient antibody titers to effectively reduce Aβ42, but an absent T cell proliferative response
and no IFNγ or IL-17 secretion after Aβ42 DNA trimer immunization minimizes the risk of inflammatory activities of the immune
system towards the self antigen Aβ42 in brain. Therefore, Aβ42 DNA trimer immunization has a high probability to be effective
and safe to treat patients with early AD. 相似文献
15.
Lia Millucci Roberto Raggiaschi Davide Franceschini Georg Terstappen Annalisa Santucci 《Journal of biosciences》2009,34(2):293-303
The highly toxic Aβ(25–35) is a peculiar peptide that differs from all the other commonly studied β-amyloid peptides because of its extremely rapid aggregation properties and enhanced neurotoxicity. We investigated Aβ(25–35) aggregation in H2O at pH 3.0 and at pH 7.4 by means of in-solution analyses. Adopting UV spectroscopy, Congo red spectrophotometry and thioflavin
T fluorimetry, we were able to quantify, in water, the very fast assembling time necessary for Aβ(25–35) to form stable insoluble aggregates and their ability to seed or not seed fibril growth. Our quantitative results,
which confirm a very rapid assembly leading to stable insoluble aggregates of Aβ(25–35) only when incubated at pH 7.4, might be helpful for designing novel aggregation inhibitors and to shed light on the
in vivo environment in which fibril formation takes place. 相似文献
16.
Rinnová Markéta Souček Milan Lebl Michal 《International journal of peptide research and therapeutics》1999,6(1):15-22
Summary The condensation of short peptides to resin-bound fragments was examined with respect to high coupling yields with only a
small molar excess of a peptide in the reaction solution. The best results were achieved by the addition of reactants (C-unprotected
peptide, DIC, and HOBt) dissolved in a so-called swelling volume of an appropriate solvent to a dry resin with an attached
N-deprotected peptide chain. Each coupling step was followed by the end-capping of unreacted resin-bound peptide with 2,4-dinitrofluorobenzene.
The substituted dinitroaniline chromophore formed in this reaction made the detection and separation of deletion peptides
easy. Both conventional and ‘swelling volume’ methods were compared on parallel syntheses of the HIV-1 protease C-terminal
78–99 fragment. The yields of the isolated heneicosapeptide were 21 and 81% in favor of the ‘swelling volume’ procedure. 相似文献
17.
Emilia Bramanti Francesco Lenci Antonella Sgarbossa 《European biophysics journal : EBJ》2010,39(11):1493-1501
We have determined the secondary structure of 1–40 β-amyloid peptides by Fourier-transform infrared spectroscopy (FTIR) and
characterized the peptide photophysical properties before and after self-assembly by using intrinsic tyrosine steady-state
and time-resolved fluorescence. All measurements were performed in the presence and absence of hypericin (Hyp), an exogenous
natural polycyclic pigment that has been shown to inhibit fibril formation and has also been used as a fluorescent probe.
We monitored the time course of the aggregation process measuring 405 nm light diffusion at 90° and used thioflavin T to reveal
the presence of fibrils. FTIR quantitative analysis evidenced a prevalent random conformation at t = 0 with and without Hyp. Fibrils showed a predominant parallel β-sheet structure and a small percentage of α-helix. The
results of fluorescence measurements showed that Hyp does significantly interact with peptides in β-sheet conformation. In
conclusion, hypericin does hinder the formation of fibrils, but the percentages of parallel β-sheets were not significantly
different from those found in samples not treated with Hyp. 相似文献
18.
Cross-linked polystyrene-ethyleneglycol acrylate resin (CLPSER) was developed for the solid-phase synthesis of peptide by introducing a cross-linker, O,O'-bis(2-acrylamidopropyl)polyethylene glycol(1900) (Acr(2)PEG), into polystyrene. The cross-linker was prepared by treating acryloyl chloride with O,O'-bis(2-aminopropyl) polyethylene glycol(1900) [(NH(2))(2)PEG] in the presence of diisopropylethylamine. The copolymer was prepared either by bulk or inverse suspension copolymerization of Acr(2)PEG(1900) and styrene using sorbitan monolaurate as the suspension stabilizer, and a mixture of ammonium peroxodisulfate and benzoyl peroxide as the radical initiators. The resin was characterized using gel-phase (13)C NMR, infrared (KBr) spectroscopic techniques and the morphological features of the resin were investigated using scanning electron microscopy photographs. CLPSER showed excellent swelling in a broad range of solvents and was found to be chemically inert to various reagents and solvents used in solid-phase peptide synthesis. To demonstrate the usefulness of the new resin in polypeptide synthesis, the support was derivatized with an 'internal reference' amino acid (norleucine) and a handle 4-(4-hydroxymethyl-3-methoxy)butyric acid. The new resin was compared with commercial supports such as Merrifield and Sheppard resins by synthesizing an acyl carrier protein (65-74) fragment under the same experimental conditions. HPLC profiles revealed the high efficiency of the newly developed support. Resin capability in peptide synthesis was further demonstrated by the solid phase synthesis of a 25-residue peptide from the E2/NS1 region hepatitis C viral polyprotein. 相似文献
19.
Bader-Yassine Diab Nathalie C. Lambert Fatima-Ezzahra L'Faqihi Patrick Loubet-Lescoulié Claude de Préval H. Coppin 《Immunogenetics》1999,49(1):36-44
The binding ability of 23 overlapping peptides, all derived from the CB11 fragment of CII, was tested on several HLA-DR molecules
associated or not with disease susceptibility. These experiments were performed on a variety of cells expressing different
HLA-DR molecules, using both indirect and direct binding assays. The CII (256–271) fragment was shown to bind to a restricted
population among which the HLA-DR molecules associated with susceptibility to rheumatoid arthritis. The results also clearly
indicate that the binding specificity of CII (256–271), among the DR4 molecules, is controlled by the nature of the HLA-DR
molecule β-chain residues 71 and 74, residues previously shown by X-ray crystallography to be involved in the HLA-DR/peptide
interaction. The human CII (256–271) peptide is thus likely to play a role in the disease process.
Received: 6 May 1998 / Revised: 16 July 1998 相似文献
20.