摘要:

AbstractThe radiolabeling of the natural octapeptide CCK8, derivatized with a cysteine residue (Cys‐Gly‐CCK8), by using the metal fragment [99mTc(N)(PNP3)]2+(PNP3 =N,N‐bis(dimethoxypropylphosphinoethyl)methoxyethylamine) is reported. The [99mTc(N)(NS‐Cys‐Gly‐CCK8)(PNP3)]+complex was obtained according to two methods (one‐step or two‐step procedure) that gave the desired compound in high yield. The complex is stable in aqueous solution and in phosphate buffer.In vitrochallenge experiments with an excess of cysteine and glutathione indicate that no transchelation reactions occur, confirming the high thermodynamic stability and kinetic inertness of this compound. Stability studies carried out in human and mouse serum, as well as in mouse liver homogenates, show that the radiolabeled compound remains intact for prolonged incubation at 37 °C. Binding properties giveKd(19.0 ± 4.6 nmol/l) andBmax(∼106sites/cell) values in A431 cells overexpressing the CCK2‐R.In vivoevaluation of the compound shows rapid and specific targeting to CCK2‐R, a fourfold higher accumulation compared to nonreceptor expressing tumors. Copyright © 2007 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.834

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractThe objective of this work was to study the inhibitory effects of antisense peptide nucleic acids (PNAs) targeted to domain II of 23S rRNA on bacterial translation and growth. In this paper, we report that PNA(G1138) or peptide‐PNA(G1138) targeted to domain II of 23S rRNA can inhibit both translationin vitro(in a cell‐free translation system) and bacterial growthin vivo. The inhibitory concentration (IC50) and the minimum inhibiting concentration (MIC) are 0.15 and 10 µM, respectively. The inhibition effect of PNA(G1138)in vitrois somewhat lower than that of tetracycline (IC50= 0.12 µM), but the MIC of peptide‐PNA(G1138) againstEscherichia coliis significantly higher than that of tetracycline (MIC = 4 µM). Further studies based on similar colony‐forming unit (CFU) assays showed that peptide‐PNA(G1138) at 10 µMis bactericidal, but the bactericidal effect is less effective than that of tetracycline. Nevertheless, the results demonstrated that the peptide‐PNA(G1138) treatment is bactericidal in a dose‐ and sequence‐dependent manner and that the G1138 site of 23S rRNA is a possible sequence target for designing novel PNA‐based antibiotics. Copyright © 2007 European Peptide Society an

ISSN:1075-2617    

DOI:10.1002/psc.835

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractTrypsin cleaves specifically peptide bonds at theC‐terminal side of lysine and arginine residues, except for ‐Arg‐Pro‐ and ‐Lys‐Pro‐ bonds which are normally resistant to proteolysis. Here we report evidence for a ‐Lys‐Pro‐ tryptic cleavage in modified oligotuftsin derivatives, Ac‐[TKPKG]4‐NH2) (1), using high‐resolution mass spectrometry and HPLC as primary methods for analysis of proteolytic reactions. The proteolytic susceptibility of ‐Lys‐Pro‐ bonds was strongly dependent on flanking residues, and the flexibility of the peptide backbone might be a prerequisite for this unusual cleavage. While ‐Lys‐Gly‐ bonds in1were rapidly cleaved, the modification of these Lys residues by the attachment of a ß‐amyloid(4–10) epitope to yield ‐Lys(X)‐Gly derivatives prevented cleavage of this bond, and provided trypsin cleavage of ‐Lys‐Pro‐ bonds, the pathway of this degradation being independent on the type of Lys‐Nε‐side chains (acetyl group, amino acid, peptide). Substitution of the Lys residues by Ala at the P′2 positions decreased the tryptic cleavage, while replacement of the bulky side chain of Thr at the P2 positions strongly increased the cleavage of ‐Lys‐Pro‐ bonds. Circular dichroism (CD) data of the modified oligotuftsin derivatives are in accord with enhanced flexibility of the peptide backbone, as a prerequisite for increased susceptibility to cleavage of ‐Lys‐Pro‐ bonds. These results obtained of oligotuftsin derivatives might have implications for the proteolytic degradation of target peptides that require specific conformational preconditi

ISSN:1075-2617    

DOI:10.1002/psc.836

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractChromogranin‐derived peptides have important and varied biological activities. They affect a wide spectrum of targets such as fungal membranes, blood vessels, myocardial cells, and pancreatic cells. Despite the biological significance and the diverse activities, the molecular mechanisms of the interactions between the peptides and the target proteins have not been well understood. Here, we studied the interaction between a chromogranin A–derived peptide (CGA40–65) and its target protein, calmodulin, with NMR spectroscopy. Calmodulin was easily prepared with standard recombinant technology, but CGA40–65 posed challenges requiring multistep procedures. The recombinantly produced peptide retained the calmodulin‐binding property of the full‐length CGA, as shown by the HSQC binding experiment. By applying resonance assignments, we identified the residues in calmodulin involved in the CGA40–65 binding. We also found that the peak changes are close to those exhibited by the peptides having the wrap‐around binding mechanism. Further analysis revealed that the CGA40–65‐induced changes are more similar to those by CaMKIp peptide than those by smMLCKp peptide among the wrap‐around binding peptides, suggesting that CGA40‐65 can be categorized as a CaMKIp‐like peptide. Our report is the first residue‐resolution mechanistic study involving chromogranin peptides and their target proteins. Our approaches should be applicable to interaction studies involving other chromogranin‐derived peptides and their cellular target proteins. Copyright © 2007 European Peptide So

ISSN:1075-2617    

DOI:10.1002/psc.837

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractThe surface properties of pure RuBisCo transit peptide (RTP) and its interaction with zwitterionic, anionic phospholipids and chloroplast lipids were studied by using the Langmuir monolayer technique. Pure RTP is able to form insoluble films and the observed surface parameters are compatible with an α‐helix perpendicular to the interface. The α‐helix structure tendency was also observed by using transmission FT‐IR spectroscopy in bulk system of a membrane mimicking environment (SDS). On the other hand, RTP adopts an unordered structure in either aqueous free interface or in the presence of vesicles composed of a zwitterionic phospholipid (POPC). Monolayer studies show that in peptide/lipid mixed monolayers, RTP shows no interaction with zwitterionic phospholipids, regardless of their physical state. Also, with the anionic POPG at high peptide ratios RTP retains its individual surface properties and behaves as an immiscible component of the peptide/lipid mixed interface. This behaviour was also observed when the mixed films were composed by RTP and the typical chloroplast lipids MGDG or DGDG (mono‐ and di‐galactosyldiacylglycerol). Conversely, RTP establishes a particular interaction with phosphatidylglycerol and cardiolipin at low peptide to lipid area covered relation. This interaction takes place with an increase in surface stability and a reduction in peptide molecular area (intermolecular interaction). Data suggest a dynamic membrane modulation by which the peptide fine‐tunes its membrane orientation and its lateral stability, depending on the quality (lipid composition) of the interface. Copyright © 2007 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/psc.838

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractSynthesis and conformational studies of a cecropin–melittin hybrid pentadecapeptide CA(1–7)MEL(2–9), and its three α, β‐dehydrophenylalanine (ΔPhe) containing analogs in water‐TFE mixtures are described. ΔPhe is placed at strategic positions in order to preserve the amphipathicity of the molecule. The wild type CAMEL0 and its three analogs, containing one, two and three ΔPhe residues namely CAMELΔPhe1, CAMELΔPhe2 and CAMELΔPhe3 respectively were synthesized in solid phase and their conformation determined by CD and NMR. CAMELΔPhe2 and CAMELΔPhe3 peptides exhibit the presence of 310‐helix and β‐turns in the former and only turns in the latter. CAMELΔPhe1 peptide was found to have a largely extended conformation. Antibacterial and hemolytic activities of the peptides were also evaluated. CAMELΔPhe2 peptide is maximally potent against bothStaphylococcus aureusATCC 259230 andEscherichia coliATCC 11303. CAMELΔPhe1 with a single ΔPhe at the center shows minimal hemolysis. Copyright © 2007 European Peptide Soc

ISSN:1075-2617    

DOI:10.1002/psc.841

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractElastin, one of the extracellular matrix components, is present in tissues requiring extensibility and resilience such as the aorta, lungs, ligaments and skin. Degradation of elastin is observed in diseases such as atherosclerosis, emphysema and metastasis. It has been suggested that degraded elastin‐derived peptides interact with a variety of cell types and are involved in development of diseases. Two nonapeptides, Ala‐Gly‐Val‐Pro‐Gly‐Leu‐Gly‐Val‐Gly (AGVPGFGVG) and Ala‐Gly‐Val‐Pro‐Gly‐Phe‐Gly‐Val‐Gly (AGVPGFGVG), exist in hydrophobic regions of elastin. In this paper, we characterized these elastin‐derived nonapeptides by macrophage migration assay. Both nonapeptides induced a maximal migration at 10−8Mand elicited the same degree of responsiveness. To investigate the role of the sixth residue of the nonapeptides, seven analog peptides in which Leu or Phe is substituted by Ile, Val, Ala, Gly, Pro, Lys or Glu were synthesized and their macrophage migration activity tested. Among the nonapeptide analogs, only Ala‐Gly‐Val‐Pro‐Gly‐Ile‐Gly‐Val‐Gly induced the migration of macrophages at the optimal concentration of 10−9Mand its responsiveness was the same as that of parent nonapeptide AGVPGFGVG. Results of the deactivation tests and the effect of lactose on macrophage migration showed that a lactose‐insensitive receptor which mainly recognizes Ala‐Gly‐Val‐Pro‐Gly‐Ile‐Gly‐Val‐Gly is presumably present on the membrane of macrophages in addition to the elastin‐binding protein (EBP) sensitive to lactose. These results suggest that Leu, Phe and Ile residues at the sixth position of elastin‐derived nonapeptides are crucial for inducing macrophage migration and in particular, Ile residue is important for the recognition by receptor insensitive t

ISSN:1075-2617    

DOI:10.1002/psc.845

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractTachystatin B is an antimicrobial and a chitin‐binding peptide isolated from the Japanese horseshoe crab (Tachypleus tridentatus) consisting of two isopeptides called tachystatin B1 and B2. We have determined their solution structures using NMR experiments and distance geometry calculations. The 20 best converged structures of tachystatin B1 and B2 exhibited root mean square deviations of 0.46 and 0.49 Å, respectively, for the backbone atoms in Cys4‐Arg40. Both structures have identical conformations, and they contain a short antiparallel β‐sheet with an inhibitory cystine‐knot (ICK) motif that is distributed widely in the antagonists for voltage‐gated ion channels, although tachystatin B does not have neurotoxic activity. The structural homology search provided several peptides with structures similar to that of tachystatin B. However, most of them have the advanced functions such as insecticidal activity, suggesting that tachystatin B may be a kind of ancestor of antimicrobial peptide in the molecular evolutionary history. Tachystatin B also displays a significant structural similarity to tachystatin A, which is member of the tachystatin family. The structural comparison of both tachystatins indicated that Tyr14and Arg17in the long loop between the first and second strands might be the essential residues for binding to chitin. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.846

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY

摘要:

AbstractMicrowave irradiation dramatically improves the efficiency of ring closing metathesis (RCM) reactions of resin‐attached peptides and the technology is illustrated by the highly selective synthesis of dicarba analogues of α‐conotoxin IMI. Copyright © 2007 European Peptide Society and John Wiley&Sons

ISSN:1075-2617    

DOI:10.1002/psc.840

出版商:John Wiley&Sons, Ltd.    

年代:2007

数据来源: WILEY