摘要:

AbstractIncreasing evidence suggests that the aggregation of the small peptide Aβ42 plays an important role in the development of Alzheimer's disease. Inhibiting the initial aggregation of Aβ42 may be an effective treatment for preventing, or slowing, the onset of the disease. Using anin vivoscreen based on the enzyme EGFP, we have searched through two combinatorially diverse peptide libraries to identify peptides capable of inhibiting Aβ42 aggregation. From this initial screen, three candidate peptides were selected and characterized. ThT studies indicated that the selected peptides were capable of inhibiting amyloid aggregation. Additional ThT studies showed that one of the selected peptides was capable of disaggregating preformed Aβ42 fibers. Copyright © 2009 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.1150

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractAngiotensin‐converting enzyme (ACE) is a key molecule of the renin–angiotensin–aldosterone system which is responsible for the control of blood pressure. For over 30 years it has become the target for fighting off hypertension. Many inhibitors of the enzyme have been synthesized and used widely in medicine despite the lack of ACE structure. The last 5 years the crystal structure of ACE separate domains has been revealed, but in order to understand how the enzyme works it is necessary to study its structure in solution. We present here the cloning, overexpression inEscherichia coli, purification and structural study of the Ala959to Ser1066region (ACE_C) that corresponds to the C‐catalytic domain of human somatic angiotensin‐I‐converting enzyme. ACE_C was purified under denatured conditions and the yield was 6 mg/l of culture. Circular dichroism (CD) spectroscopy indicated that 1,1,1‐trifluoroethanol (TFE) is necessary for the correct folding of the protein fragment. The described procedure can be used for the production of an isotopically labelled ACE959–1066protein fragment in order to study its structure in solution by NMR spectroscopy. Copyright © 2009 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.1151

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractUsing the unique quantitative capabilities of hyperspectral confocal microscopy combined with multivariate curve resolution, a comparative approach was employed to gain a deeper understanding of the different types of interactions of antimicrobial peptides (AMPs) with biological membranes and cellular compartments. This approach allowed direct comparison of the dynamics and local effects of buforin II, magainin II, and arenicin with nanoporous silica bead supported bilayers and livingE. coli. Correlating between experiments and comparing these responses have yielded several important discoveries for pursuing the underlying biophysics of bacteriocidal specificity and the connection between structure and function in various cellular environments. First, a novel fluorescence method for direct comparison of a model and living system is demonstrated by utilizing the membrane partitioning and environmental sensitivity of propidium iodide. Second, measurements are presented comparing the temporal dynamics and local equilibrium concentrations of the different antimicrobial agents in the membrane and internal matrix of the described systems. Finally, we discuss how the data lead to a deeper understanding of the roles of membrane penetration and permeabilization in the action of these AMPs. Copyright © 2009 European Peptide Society and John Wiley&Sons, Ltd

ISSN:1075-2617    

DOI:10.1002/psc.1152

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractIn an effort to develop a structured peptide scaffold that lacks a disulfide bond and is thus suitable for molecular recognition applications in the reducing environment of the cytosol, we investigated engineered versions of the trpzip class of β‐hairpin peptides. We have previously shown that even most highly folded members of the trpzip class (i.e. the 16mer peptideHP5W4) are substantially destabilized by the introduction of mutations in the turn region and therefore not an ideal peptide scaffold. To address this issue, we used a FRET‐based live cell screening system to identify extended trpzip‐type peptides with additional stabilizing interactions. One of the most promising of these extended trpzip‐type variants is the 24merxxtz1‐peptide with the sequence KAWTHDWTWNPATGKWTWLWRKNK. A phage display library of this peptide with randomization of six residues with side chains directed towards one face of the hairpin was constructed and panned against immobilized streptavidin. We have also explored the use ofxxtz1‐peptide for the presentation of an unstructured peptide ‘loop’ inserted into the turn region. Although NMR analysis provided no direct evidence for structure in thexxtz1‐peptide with the loop insertion, we did attempt to use this construct as a scaffold for phage display of randomized peptide libraries. Panning of the resulting libraries against streptavidin resulted in the identification of peptide sequences with submicromolar affinities. Interestingly, substitution of key residues in the hairpin‐derived portion of the peptide resulted in a 400‐fold decrease inKd, suggesting that the hairpin‐derived portion plays an important role in preorganization of the loop region for molecular recognition. Copyright © 2009 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.1153

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe infrared (IR), vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) spectra of short cationic sequential peptides (L‐Lys‐L‐Ala‐L‐Ala)n(n= 1, 2, and 3) were measured over a range of temperatures (20–90 °C) in aqueous solution at near‐neutral pH values in order to investigate their solution conformations and thermally induced conformational changes. VCD spectra of all three oligopeptides measured in the amide I′ region indicate the presence of extended helical polyproline II (PPII)‐like conformation at room temperature. UV‐ECD spectra confirmed this conclusion. Thus, the oligopeptides adopt a PPII‐like conformation, independent of the length of the peptide chain. However, the optimized dihedral angles ϕ and ψ are within the range −82 to −107° and 143–154°, respectively, and differ from the canonical PPII values. At elevated temperatures, the observed intensity and bandshape variations in the VCD and ECD spectra show that the PPII‐like conformation of the Lys‐Ala‐Ala sequence is still preferred, being in equilibrium with an unordered conformer at near‐neutral pH values within the range of temperatures from 20 to 90 °C. This finding was obtained from analysis of the temperature‐dependent spectra using the singular value decomposition method. The study presents KAA‐containing oligopeptides as conformationally stable models of biologically important cationic peptides and proteins. Copyright © 2009 Eur

ISSN:1075-2617    

DOI:10.1002/psc.1154

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractNonenzymatic protein glycation is caused by a Schiff's base reaction between the aldehyde groups of reducing sugars and the primary amines of proteins. These structures may undergo further Amadori rearrangement and free radical‐mediated oxidation to finally generate irreversible advanced glycation end products (AGEs). One of the factors known to modulate the glycation of proteins is glutathione, the most abundant nonprotein thiol tripeptide with the γ‐linkage, H‐Glu(Cys‐Gly‐OH)‐OH (GSH). Screening for products formed by GSH withD‐glucose is an essential step in understanding the participation of GSH in glycation (the Maillard) reaction. Under the conditions used in these studies we observedN‐(1‐deoxy‐D‐fructos‐1‐yl)‐pyroglutamic acid as the major glycation product formed in the mixtures of GSH and glucosein vitro. A RP HPLC/MS and tandem MS analyses of the GSH/glucose mixtures revealed that cleavage of theN‐terminal glutamic acid and the formation of pyroglutamic acid‐related Amadori product were accompanied by generation of Cys‐Gly‐derived Amadori and thiazolidine compounds. Copyright © 2009 European Pep

ISSN:1075-2617    

DOI:10.1002/psc.1159

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY