bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulmonary function abnormalities in children treated with whole lung irradiation
Authors: Weiner Daniel J. , Maity Amit , Carlson Claire A. , Ginsberg Jill P.
Published: May 2005

Background

We sought to determine the prevalence of abnormal pulmonary function tests (PFTs) in a cohort of children who had received whole lung irradiation (WLI) for treatment of metastatic disease.

Procedure

This was a retrospective (1988–2003) chart review that included all children treated at our institution with WLI who had undergone PFT. Data abstracted included oncologic diagnosis, radiation dose and fractionation, spirometry (FVC, FEV1, FEV1/FVC, FEF25%–75%), plethysmography (TLC, FRC, RV, RV/TLC), diffusing capacity (DLCO), and respiratory muscle strength (MIP, MEP). PFTs were normalized according to standard deviation (Z) scores.

Results

Thirty patients were identified who had one or more PFT. The incidence of mild, moderate, or severe reductions in FEV1 was 30%, 10%, and 10%, respectively, with 50% having normal FEV1. Seventeen percent of patients had mild reduction in total lung capacity (TLC), while 13% and 30% had moderate or severe reductions. Thirty‐eight percent had mild reductions in diffusing capacity, while 29% and 14% had moderate or severe reductions.

Conclusions

Pulmonary function abnormalities were common in this cohort of children treated with WLI, and may be progressive in nature. Further studies are warranted to identify patients at highest risk. © 2005 Wiley‐Liss, Inc.
Preparation of aqueous anionic poly(urethane‐urea) dispersions. Influence of the structure and molecular weight of the macrodiol on the dispersion and polymer properties
Authors: Durrieu Vanessa , Gandini Alessandro
Published: May 2005

Aqueous poly(urethane‐urea) dispersions were prepared by the prepolymer mixing technique, without any organic solvent, using two aliphatic diisocyanates (α,α,α′,α′‐tetramethyl‐1,3‐xylylene diisocyanate and isophorone diisocyanate) and various macrodiols, in conjunction with a fixed proportion of emulsifying agent (dimethylol propionic acid, neutralised with triethylamine) and the same chain extender (1,2‐ethylene diamine). The properties of both the dispersions and the dried polymer films were characterised as a function of the two main parameters studied in this investigation, viz the structure of the macrodiols and their molecular weight, in order to establish criteria leading to optimised performances in terms of dispersion stability, particle size, and polymer film properties. Copyright © 2005 Society of Chemical Industry
Preparation of flexible polyhedral particles via concentrated emulsion templating polymerization
Authors: Xiang Aimin , Du Zhongjie , Zeng Qinghua , Zhang Chen , Li Hangquan
Published: May 2005

This paper presents recent efforts on the preparation of flexible polyhedral particles via concentrated emulsion templating polymerization in which the hydrophilic monomer (acrylamide) and hydrophobic monomer (butyl acrylate) are polymerized simultaneously in the continuous and dispersed phase, respectively. Such templating polymerization has been enhanced in our systems owing to the introduction of acrylamide monomer and their higher polymerization rate in continuous phase as compared with butyl acrylate in dispersed phase. Diffusion between the different phases was also inhibited. Furthermore, the stability of the concentrated emulsion and the molecular weight of the produced poly(butyl acrylate) were found to be significantly affected by the amount of redox initiator. The morphology of the particles could be controlled by varying the volume fraction of the dispersed phase and the polyhedral particles were achieved at higher volume fraction. Copyright © 2005 Society of Chemical Industry
Melt miscibility and mechanical properties of metallocene linear low‐density polyethylene blends with high‐density polyethylene: influence of comonomer type
Authors: Hussein Ibnelwaleed A
Published: May 2005

In this paper, the implications of melt miscibility on the thermal and mechanical properties of linear low‐density polyethylene (LLDPE)/high‐density polyethylene (HDPE) blends were assessed with respect to the influence of the comonomer type. The influence of the latter was examined by selecting one butene LLDPE and one octene LLDPE of very similar weight‐average molecular weight (Mw), molecular‐weight distribution (MWD) and branch content, keeping the comonomer type as the only primary molecular variable. Each of the two metallocene LLDPEs was melt‐blended with the same HDPE at 190 °C in a Haake melt‐blender. The rheological, thermal and mechanical properties were measured by the use of an ARES rheometer, differential scanning calorimeter and Instron machine, respectively. The rheological measurements, made over the linear viscoelastic range, suggested no significant influence of the branch type on the melt miscibility. The rheology results are in agreement with those obtained from previous transmission electron microscopy (TEM) and small‐angle neutron scattering (SANS) studies. The dynamic shear viscosity and total crystallinity of the metallocene (m)‐LLDPE blends with HDPE followed linear additivity. At small strains, the branch type has little or no influence on the melt miscibility and solid‐state properties of the blends. Even the large‐strain mechanical properties, such as tensile strength and elongation at break, were not influenced by the comonomer type. However, the ultimate tensile properties of the HDPE‐rich blends were poor. Incompatibility of the HDPE‐rich blends, as a result of the weak interfaces between the blend components, is suggested to develop at large strains. Copyright © 2005 Society of Chemical Industry
Social‐cognitive correlates of adjustment to prostate cancer
Authors: Roberts Katherine J. , Lepore Stephen J. , Helgeson Vicki
Published: May 2005

This study examined whether social support might enhance health‐related quality of life in men (n=89) treated for localized prostate cancer by improving their ability to cognitively process their cancer experience. Data were collected using two, structured in‐person interviews and abstracting medical records. The baseline interview was within several months (T1) after treatment for cancer, and follow‐up was 3 months later (T2). Most men (61.8%) were treated by radical prostatectomy. Results showed that T1 social support was positively related to T2 mental functioning, and this relation appeared to be mediated by T1 indicators of cognitively processing, intrusive thoughts and searching for meaning. These findings suggest that supportive social relations may improve mental functioning by helping men cognitively process their prostate cancer experience. Copyright © 2005 John Wiley & Sons, Ltd.
The development of a distraction‐based coping intervention for women waiting for genetic risk information: a phase 1 qualitative study
Authors: Phelps Ceri , Bennett Paul , Iredale Rachel , Anstey Sally , Gray Jonathon
Published: May 2005

This study explored the emotional and coping responses of women referred for cancer genetic risk assessment and the acceptability of a written distraction‐based coping intervention. Fifteen women recently referred into the Cancer Genetics Service for Wales (CGSW) took part in a focus group study. The women were divided into two groups, each of which met twice. During the first session, each group discussed their psychological responses to the referral and how they coped with their worries. Women discussed the potential role of the intervention in minimising distress. Analysis of the transcripts revealed that most women welcomed the referral to CGSW and that it did not create distress. However, there was concern for family members and anxiety about subsequent stages of the assessment process. The intervention was considered appropriate and potentially effective. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis and bioactivity of some new N‐aryl/alkyl/cyclohexyl‐N′‐(2,3‐dihydro‐2‐oxo‐4H‐benz[e][1,3,2]oxazaphosphorin‐2‐yl) ureas
Authors: Kiran YB , Gunasekar D , Devendranath Reddy C , Suresh Reddy C , Tran Kevin , Le Thanh , Darrell Berlin K , Srinivasan S , Charitha Devi M
Published: May 2005

Several new substituted oxazaphosphorinyl urea derivatives of the type RR′P(O)NHC(O)NHR″ were synthesized from α‐(3‐chloro‐4‐fluoroanilino)‐o‐cresol by reaction with chlorides of aryl/alkyl/cyclohexyl carbamidophosphoric acids in the presence of triethylamine at 0–50 °C. Their significant insecticidal and antimicrobial activity and promotion of Rhizobium bacteria growth in the soil without effect on the host tissue suggests their possible commercial application as ecofriendly pesticides and antimicrobial agents. Copyright © 2005 Society of Chemical Industry
Protein design as a challenge for peptide chemists
Authors: Tuchscherer Gabriele , Mutter Manfred
Published: May 2005

All efforts to turn the ultimate goal in protein de novo design into reality–the construction of new macromolecules with predetermined three‐dimensional structure and well‐defined functionality–failed because the mechanism of folding has still to be unravelled. In the present review, various attempts to apply synthetic tools for inducing native‐like structural features in peptides in order to bypass the folding problem are described. Besides well‐established methods for the nucleation and stabilization of secondary structures, e.g. α‐helices, β‐sheets and β‐turns, topological templates as ‘built‐in’ folding devices have more recently become the key elements for the induction of protein‐like folding units (template‐assembled synthetic proteins, TASP). Progress in the synthetic strategy and structural characterization of this new type of macromolecules opens the way for the design of functional TASP molecules.
N,O‐bisFmoc derivatives of N‐(2‐hydroxy‐4‐methoxybenzyl)‐amino acids: Useful intermediates in peptide synthesis
Authors: Johnson Tony , Quibell Martin , Sheppard Robert C.
Published: May 2005

2‐Hydroxy‐4‐methoxybenzyl‐amino acid residues inhibit interchain association in solid phase peptide synthesis. They are easily introduced through their N,O‐bisFmoc derivatives. Preparation of a range of these derivatives is described.
Binary synthesis of multicomponent peptide mixtures by the portioning–mixing technique
Authors: Sebestyén Ferenc , Szalatnyai Tüunde , Durgo Joseph A. , Furka Árpád
Published: May 2005

By introducing a new operation (non‐coupling), our portioning–mixing method has become suitable for preparing binary peptide libraries. We demonstrate that all the expected components of a simple library are present in the mixture. The number of components in such libraries, the molar ratio of peptides as well as the possibilities of screening are discussed.
Synthesis, characterization and biocompatibility of PEGA resins
Authors: Auzanneau France‐Isabelle , Meldal Morten , Bock Klaus
Published: May 2005

Three types of beaded polyethylene glycol polyacrylamide copolymers (PEGA) with a high content of polyethylene glycol (PEG) were synthesized by inverse suspension polymerization and characterized for peptide synthesis and with respect to their physical properties. Several peptides of high purity have been synthesized on the resin. The properties which were determined were loading of amino group, swelling, bead size distribution, porosity, flexibility and compatibility with active biomolecules. A loading of 0.35 mmol/g has been obtained and the swelling was excellent in solvents of various polarities ranging from water to dichloromethane. The 13C‐NMR T1‐relaxation times of a resin containing a peptide were determined in DMSO‐d6 and the resin was found to exhibit a behaviour similar to the components in free solution.
Synthesis and conformational studies of peptides containing TOAC, a spin‐labelled Cα,α‐disubstituted glycine
Authors: Toniolo Claudio , Valente Ezio , Formaggio Fernando , Crisma Marco , Pilloni Giuseppe , Corvaja Carlo , Toffoletti Antonio , Martinez Gary V. , Hanson M. Paul , Millhauser Glenn L. , George Clifford , Flippen‐Anderson Judith L.
Published: May 2005

A variety of host L‐alanine homo‐peptides (to the pentamer) containing one or two spin‐labelled TOAC (2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐4‐amino‐4‐carboxylic acid) residues were synthesized by solution methods and fully characterized. The conformational features of the terminally blocked, doubly spin‐labelled–TOAC–(Ala)2–TOAC–Ala– pentapeptide were examined in the crystal state by X‐ray diffraction and in solution using a combination of techniques (Fourier transform infrared, circular dichroism, cyclic voltammetry and electron spin resonance) in comparison with singly labelled shorter peptides. The 310‐helical structure of the pentapeptide, promoted by the two Cα,α‐disubstituted glycines under favourable experimental conditions, allows an interaction to take place between the two nitroxide TOAC side chains spaced by one turn of the helix. Taken together, these results suggest that TOAC is an excellent probe for exploring bends and helices in doubly labelled peptides.
Synthesis and lodination of human (phenylalanine13, tyrosine19) melanin‐concentrating hormone for radioreceptor assay
Authors: Drozdz Roma , Eberle Alex N.
Published: May 2005

An analogue of human melanin‐concentrating hormone (MCH) suitable for radioiodination was designed in which Tyr13 and Val19 of the natural peptide were replaced by phenylalanyl and tyrosyl residues: [Phe13, Tyr19] ‐MCH. The peptide was synthesized by the continuous‐flow solid‐phase methodology using Fmocstrategy and Polyhipe PA 500 and PEG‐PS resins. The linear MCH peptides with either acetamidomethyl‐protected or free cysteinyl residues were purified to homogeneity and cyclized by iodine oxidation, yielding the final product with the correct molecular weight of 2434.61. Radioiodination of the C‐terminal tyrosine was carried out enzymatically using solid‐phase bound glucose oxidase/lactoperoxidase, followed by purification on a reversed‐phase mini‐column and by high‐pressure liquid chromatography. The resulting [125I]‐[Phe13, Tyr19]‐MCH tracer was the first radiolabelled MCH peptide suitable for radioreceptor assay: saturation binding analysis using mouse G4F‐7 melanoma cells demonstrated the presence of 1090 MCH receptors per cell. The dissociation constant (KD) was 1.18 × 10−10 M, indicating high‐affinity MCH receptors on these cells. MCH receptors were also found in other cell lines such as mouse B16‐F1 and G4F and human RE melanoma cells as well as in PC12 and COS‐7 cells. Competition binding analyses with a number of other peptides such as α‐MSH, neuropeptide Y, substance P and pituitary adenylate cyclase activating peptide, demonstrated that the binding to the MCH receptor is specific. Atrial natriuretic factor was found to be a weak competitor of MCH, indicating topological similarities between MCH and ANF when interacting with MCH receptors.
An exploration of the effects of L‐ and D‐tetrahydroisoquinoline‐3‐carboxylic acid substitutions at positions 2,3 and 7 in cyclic and linear antagonists of vasopressin and oxytocin and at position 3 in arginine vasopressin
Authors: Manning Maurice , Cheng Ling Ling , Stoev Stoytcho , Bankowski Krzysztof , Przybyiski Jozef , Klis Wieslaw A. , Sawyer Wilbur H. , Wo Nga Ching , Chan W. Y.
Published: May 2005

We have investigated the effects of mono‐substitutions with the conformationally restricted amino acid, 1,2,3,4 tetrahydroisoquinoline‐3‐carboxylic acid (Tic) at position 3 in arginine vasopressin (AVP), at positions 2, 3 and 7 in potent non‐selective cyclic AVP V2/V1a antagonists, in potent and selective cyclic and linear AVP V1a antagonists, in a potent and selective oxytocin antagonist and in a new potent linear oxytocin antagonist Phaa‐D‐Tyr(Me)‐Ile‐Val‐Asn‐Orn‐Pro‐Orn‐NH2 (10). We report here the solid‐phase synthesis of peptide 10 together with the following Tic‐substituted peptides: 1, [Tic3]AVP; 2, d(CH2)5[D‐Tic2]VAVP; 3, d(CH2)5[D‐Tyr(Et)2Tic3]VAVP; 4, d(CH2)5[Tic2Ala‐NH29]AVP; 5, d(CH2)5[Tyr(Me)2, Tic3, Ala‐NH29]AVP; 6, d(CH2)5 [Tyr(Me)2, Tic7]AVP; 7, Phaa‐D‐Tyr(Me)‐Phe‐Gln‐Asn‐Lys‐Tic‐Arg‐NH2; 8, desGly‐NH2,d(CH2)5[Tic2,Thr4]OVT; 9, desGly‐NH2d(CH2)5[Tyr(Me)2Thr4, Tic7]OVT; 11, Phaa‐D‐Tic‐Ile‐Val‐Asn‐Orn‐Pro‐Orn‐NH2, using previously described methods. The protected precursors were synthesized by the solid‐phase method, cleaved, purified and deblocked with sodium in liquid ammonia to give the free peptides 1–11 which were purified by methods previously described. Peptides 1–11 were examined for agonistic and antagonistic potency in oxytocic (in vitro, without Mg2+) and AVP antidiuretic (V2‐receptor) and vasopressor (V1a‐receptor) assays. Tic3 substitution in AVP led to drastic losses of V2, V1a and oxytocic agonistc activities in peptide 1.L‐ and D‐Tic2 substitutions led to drastic losses of anti‐V2/anti‐V1a and anti‐oxytocic potencies in peptides 2, 4, 8 and 11 (peptide 2 retained substantial anti‐oxytocic potency; pA2 = 7.25 ± 0.25). Whereas Tic3 substitution in the selective V1a antagonist d(CH2)5[Tyr(Me)2, Ala‐NH29]APV(C) led to a drastic reduction in anti‐V1a potency (from anti‐V1a pA2) 8.75 to 6.37 for peptide 5, remarkably, Tic3 substitution in the V2/V1a antagonist d(CH2)5[D‐Tyr(Et)2]VAVP(B) led to full retention of anti‐V2 potency and a 95% reduction in anti‐V1a potency. With an anti‐V2 pA2 = 7.69 ± 0.05 and anti‐V1a pA2 = 6.95 ± 0.03, d(CH2)5[D‐Tyr(Et)2,Tic3]VAVP exhibits a 13‐fold gain in anti‐V2/anti‐V1a selectivity compared to (B). Tic7 substitutions are very well tolerated in peptides 6, 7 and 9 with excellent retention of the characteristic potencies of the parent peptides. The findings on the effects of Tic3 substitutions reported here may provide promising leads to the design of more selective and possibly orally active V2 antagonists for use as pharmacological tools and as therapeutic clinical agents for the treatment of the syndrome of the inappropriate secretion of antidiuretic hormone (SIADH).
Multiple synthesis by the multipin method as a methodological tool
Authors: Bray Andrew M. , Valerio Robert M. , Dipasquale Angela J. , Greig Joy , Maeji N. Joe
Published: May 2005

The multipin method of peptide synthesis is demonstrated as a potent methodological tool, where large numbers of comparative studies can be performed concurrently. Two studies are presented. In each study, the test peptides were simultaneously synthesized, and the products examined by high throughput ion spray mass spectrometry and reverse‐phase HPLC. In the first study, comprising 24 experiments, peptides 1 (AELFSTHYLAFKEDYSQ‐NH2) and 2 (LKDFRVYFREGRDQLWKGPG‐NH2) were prepared using Fmoc‐Axx/BOP/HOBt/NMM (100: 100: 100: 150 mM) and Fmoc‐Axx/HATU/HOAt/NMM (100: 100: 100: 150 mM) with 60.90 and 120 min coupling times. The two reagent combinations were found to give comparable results. The second study compared the N‐terminal coupling of Fmoc‐Asn‐OH, Fmoc‐Asn(Mbh)‐OH, Fmoc‐Asn(Mtt)‐OH, Fmoc‐Asn(Tmob)‐OH and Fmoc‐Asn(Trt)‐OH in the synthesis of seven test peptides: 3, NVQAAIDYIG‐cyclo(Kp); 4, NTVQAAIDYIG‐cyclo(KF); 5, NRVYVHPFNL; 6, NRVYVHPFHL: 7, NEAYVHDAPVRSLN: 8, NQLVVPSEGLYLIYSQVLFK. 9, NPNANPNANPNA. A total of 33 experiments were performed. Peptides 3 and 4 were selected to highlight the effect of steric bulk of each Asn derivative on coupling efficiency. Reagent efficiency, as measured by target peptide purity, was as follows: Fmoc‐Asn(Tmob)‐OH > Fmoc‐Asn‐OH > Fmoc‐Asn(Mtt)‐OH = Fmoc‐Asn(Trt)‐OH > Fmoc‐Asn(Mbh)‐OH.
Antiovulatory antagonists of LHRH related to antide
Authors: Flouret George , Arnold Zdzislaw S. , Majewski Tadeusz , Petousis Nikolaos H. , Mahan Kevin , Farooqui Firdous , Blum Katherine A. , Konopinska Danuta , Natarajan Swaminathan , Crich David
Published: May 2005

We report 104 analogues of the potent antiovulatory antagonist of LHRH, N‐Ac‐D‐Nal‐D‐Cpa‐D‐Pal‐Ser‐Lys(Nic)‐D‐Lys(Nic)‐Leu‐Ilys‐Pro‐D‐Ala‐NH2, Antide. We replaced the Nic group in Antide with other acyl substituents to modulate size, hydrophilicity or basicity of the molecule, we also replaced th Lys residues with shorter basic amino acids, and made cyclic 5/6 analogues as well as position 5 or 6 dimers. We substituted Ilys8 with other alkyl groups and acyl derivatives. When injected in 0.1% DMSO in water in a typical antiovulatory (AO) assay, Antide gives six rats ovulating out of eight (6/8) at 2 μg, 4/8 at 4 μg, and the histamine release assay (HRA), ED50 is >300 μg/ml; [Lys(N‐Isobutyl)8]Antide gave 2/8 at 2 μg/rat; [Lys (8‐Qis)5]Antide gave 1/8 at 1 μg, and 0/8 at 2 μg, and in the HRA ED50, 22 μg/ml; [D‐Lys(8‐Qis)6]Antide gave 4/8 at 1 μg and 0/8 at 2 μg, and in the HRA, ED50 was 27 μg/ml; [Lys(8‐Qic)8] gave 5/8 at 1 μg, 1/8 at 2 μg/ [Lys(2‐Pyc)5]Antide gave 5/8 at 1 μg and 0/8 at 2 μg, and in the HRA ED50 was 116 μg/ml; [D‐Lys (2‐Pyc)6]Antide gave 3/8 at 1 μg, and in the HRA, ED50 was 100 ‐ >300 μg/ml; [Lys(2‐Pyc)5,D‐Lys(2‐Pyc)6]Antide gave 2/8 at 1 μg. The substitutions of the Nic groups of Antide at Lys5 or D‐Lys6 with 8‐Qis or with 2‐Pyc groups seem to give highly potent antiovulatory antagonists of LHRH and constitute significant new leads to generate potent antiovulatory compounds endowed with moderate or low histamine release.
A synthetic substrate assay for the gamma‐secretase of the β‐A4 amyloid of alzheimer's disease
Authors: Evin Geneviève , Beyreuther Konrad , Masters Colin L.
Published: May 2005

γ‐secretase, the endoprotease which releases the C‐terminus of βA4 amyloid peptide, cleaves within the hydrophobic transmembrane domain of the amyloid precursor protein. In order to obtain a substrate for γ‐secretase, a dodecapeptide which spans the cleavage site was synthesized, labelled with 125‐iodine and conjugated to an agarose gel. A radiometric solid‐phase assay was developed using this immobilized substrate. Peptide products were separated by reverse‐phase HPLC and TLC to allow characterization of the cleavage site(s).
Immunogenicity of dinitrocarboxyphenylated melittin: The influence of C‐terminal chain shortening, N‐terminal substitution and prolin insertion at positions 5 and 10
Authors: Zhao Zhenjun , Rolli Hanspeter , Schneider Conrad H.
Published: May 2005

Peptides derived from the bee‐venom melittin were fitted with the haptenic group dinitrocarboxyphenyl(Dncp) and tested in out‐bred guinea pigs for immunogenicity by measuring the IgG anti‐Dncp antibody response by ELISA. Dncp‐conjugates comprising virtually the entire melittin proved to be strong immunogens producing antibody responses comparable to those of proteins. Weak responses were obtained with considerably shortened seqences. Conjugates with N‐terminal Dncp gave markedly reduced antibody responses compared to peptides with C‐terminal Dncp. An N‐terminal biotinyl substituent abolished the immune response whereas N‐terminal lauryl and caprylyl had little effect. Insertion of L‐proline into a hexadecapeptide conjugate abolishing the possibility of helix formation gave an immunogen to which individual animals clearly responded on a low level. Oligomerisation, but not the cytolytic activity of melittin peptides, may contribute to the immunogenicities observed.
Highly potent side chain–main chain cyclized dermorphin–deltorphin analogues: An integrated approach including synthesis, bioassays, NMR spectroscopy and molecular modelling
Authors: Ro Seonggu , Zhu Qin , Lee Chang‐Woo , Goodman Murray , Darlak Krzysztof , Spatola Arno F. , Chung Nga N. , Schiller Peter W. , Malmberg Annika B. , Yaksh Tony L. , Burks Thomas F.
Published: May 2005

Our continuing efforts to study structure–activity relationships of peptide opioids have resulted in the synthesis of a series of cyclic opioids related to dermorphins and deltorphins. The biological activities of the compounds have been determined and the conformational analyses carried out using 1H‐NMR spectroscopy and molecular modelling. The three compounds in the series Tyr‐c[D‐Orn‐Phe‐Ala], Tyr‐c[D‐Lys‐Phe‐Ala], and Tyr‐c[A2Bu‐Phe‐Ala‐Leu] are cyclized via a lactam bridge from the side‐chain of the residue at the second position with the carboxyl terminus of each compound. The molecules incorporate 12‐, 13‐ and 14‐membered rings, respectively. They include a phenylalanine at the third position which is a distinguishing characteristic of dermorphins and deltorphins. The guinea pig ileum and mouse vas deferens assays show that the compounds are highly active at both μ‐ and δ‐opioid receptors. The compounds are all highly effective antinociceptive agents as measured by the intrathecal rat hot plate test. Conformational analyses of the molecules indicate that they can adopt topochemical arrays required for bioactivity at both μ‐ and δ‐receptors which explains their high activity in both guinea pig ileum and mouse vas deferens in vitro assays. The results support our models for μ‐ and δ‐receptor activity for constrained peptide opioids.
Solid‐Phase synthesis of peptide nucleic acids
Authors: Christensen Leif , Fitzpatrick Richard , Gildea Brian , Petersen Kenneth H. , Hansen Henrik F. , Koch Troels , Egholm Michael , Buchardt Ole , Nielsen Peter E. , Coull James , Berg Rolf H.
Published: May 2005

Peptide nucleic acids (PNA) were synthesized by a modified Merrifield method using several improvements. Activation by O‐(benzotriazol‐1‐yl)‐1,1,3,3‐tetramethyluronium hexafluorophosphate in combination with in situ neutralization of the resin allowed efficient coupling of all four Boc‐protected PNA monomers within 30 min. HPLC analysis of the crude product obtained from a fully automated synthesis of the model PNA oligomer H‐CGGACTAAGTCCATTGC‐Gly‐NH2, indicated an average yield per synthetic cycle of 97.1%. N1‐benzyloxycarbonyl‐N63‐methylimidazole triflate substantially outperformed acetic anhydride as a capping reagent. The resin‐bound PNAs were successfully cleaved by the ‘low–high’ trifluoromethanesulphonic acid procedure.
Synthetic S‐(2,3‐dihydroxypropyl)‐cysteinyl peptides derived from the N‐terminus of the cytochrome subunit of the photoreaction centre of Rhodopseudomonas viridis enhance murine splenocyte proliferation
Authors: Metzger Jörg W. , Beck‐Sickinger Annette G. , Loeit Manuel , Eckert Marianne , Bessler Wolfgang G. , Jung Günther
Published: May 2005

Various lipopeptides representing the N‐terminal part of the cytochrome subunit of the photosynthetic reaction centre from the purple bacterium Rhodopseudomonas virdis were prepared by solid‐phase peptide synthesis. These lipopeptides consisted of a S‐[2,3‐dihydroxypropyl]‐cysteinyl (Dhc) residue N‐terminally coupled to the nonapeptide FEPPPATTT. Different numbers of palmitoyl (Pam) chains were attached to Dhc via ester and/or amide bonds. The lipopeptide Dhc(Pam)2‐FEPPPATTT containing two ester‐bonded palmitoyl residues and a free N‐chain lipopeptide Pam‐Dhc(Pam)‐FEPPPATTT containing one amide‐ and one ester‐bonded palmitoyl residues, the two‐chain lipopeptide Pam‐Dhc(Pam)‐FEPPPATTT containing one amide‐ and one ester‐bonded palmitoyl residue, and the N‐terminally elongated lipopeptide SLVAG‐Dhc(Pam)2‐FEPPPATTT were less active. The nonapeptide FEPPPATTT and the decapeptide Dhc‐FEPPPATTT were only merginal splenocyte activators, even at concentrations as high as 1 μM. Thus, lipopeptide Dhc(Pam)2‐FEPPPATTT constitutes the first potent splenocyte stimulating Dhc‐lipopeptide described so far that contains only two fatty acid residues.
Anchor‐linked intermediates in peptide amide synthesis are caused by dimeric anchors on the solid supports
Authors: Flechsler Insa , Beck‐Sickinger Annette G. , Stephan Holger , Sheppard Robert , Jung Günther
Published: May 2005

Cleavage and kinetic studies have been carried out using commercially obtained H‐Tyr(tBu)‐5‐(4′‐aminomethyl‐3′,5′‐dimethoxyphenoxy)valeric acid‐TentaGelS (H‐Tyr(tBu)‐4‐ADPV‐TentaGelS) and H‐Tyr (tBu)‐4‐ADPV‐Ala‐aminomethyl‐resin (H‐Tyr(tBu)‐4‐ADPV‐AM‐resin) prepared from commercially available resin and loaded with commercially available Fmoc‐4‐ADPV‐OH amide anchor. Cleavage with pure trifluoroacetic acid (TFA) gave the intermediate H‐Tyr‐4‐ADPV‐NH2, which was then degraded to H‐Tyr‐NH2, and cleavage with TFA/dichloromethane (1:9) yielded H‐Tyr‐4‐ADPV‐NH2 which could be isolated in preparative amounts. Cleavage reactions with 15N‐labelled H‐Ala‐4‐ADPV‐[15N]‐Gly‐AM‐resin yielded the intermediate H‐Ala‐4‐ADPV‐NH2, which contained no 15N as demonstrated by 1H‐NMR. The analysis of the commercial Fmoc‐4‐ADPV‐OH amide anchor showed the presence of Fmoc‐4‐ADPV‐4‐ADPV‐OH as an impurity in high amounts. This dimeric anchor molecule is the cause of formation of the anchor‐linked peptide intermediate obtained during the cleavage from the resin. The particularly high acid‐lability of the amide bond between the two ADPV moieties was utilized to synthesize sidechain and C‐terminally 4‐ADPV protected pentagastrin on a double‐anchor resin, and to cleave it using 5% trifluoroacetic acid in dichloromethane. This method may offer a new way for the synthesis of protected peptide amides with improved solubility to be used in fragment condensation.
Determination of disulphide bridges in PG‐2, an antimicrobial peptide from porcine leukocytes
Authors: Harwig Sylvia S. L. , Swiderek Kristine M. , Lee Terry D. , Lehrer Robert I.
Published: May 2005

We determined the cysteine connectivity of protegrin PG‐2, a leukocyte‐derived antimicrobial peptide, by performing sequential enzyme digestions with chymotrypsin and thermolysin, and monitoring each digest by direct liquid chromatography–electrospray mass spectrometric analysis. This approach resolved the disulphide pairing pattern unambiguously with only picomolar amounts of PG‐2. The inferred cysteine connectivity was confirmed by traditional amino acid composition analyses using nanomolar amounts of the protegrin. The results suggest that protegrins will assume a tachyplesin‐like, disulphide‐stabilized antiparallel β‐sheet configuration in solution.
Identification of avidin and streptavidin binding motifs among peptides selected from a synthetic peptide library consisting solely of D‐amino acids
Authors: Gissel Birgitte , Jensen Martin Roland , Gregorius Klaus , Elsner Henrik I. , Svendsen Ib , Mouritsen Søren
Published: May 2005

Peptides consisting solely of D‐amino acids (D‐peptides) as opposed to their L‐counterparts (L‐peptides) are resistant towards proteolytic degradation in the organism and may therefore be useful in future efforts to develop new stable peptide‐based drugs. Using the random synthetic peptide library technique several L‐ and D‐peptides, capable of binding to both avidin and streptavidin, were found. The L‐peptides contained the previously described HPQ/M motifis, and among the D‐peptides three binding motifs could be identified, of which the most frequently found one contained an N‐terminal aliphatic hydrophobic amino acid (V, L or I) and an aromatic amino acid (Y or F) on the second position. At the third position in this motif several different amino acid residues were found, although N was the most frequent. Peptides representing two of the D‐motifs were synthesized as well as peptides containing the HPQ/M motifs, and their binding properties were examined. Although the D‐peptides were originally selected using avidin they also inhibited binding between immobilized biotin and soluble streptavidin as well as avidin. The IC50 of some of the peptides were approximately 105 times higher than the IC50 for biotin but some had a lower IC50 than iminobiotin. The D‐peptides, which were originally selected from the library using avidin, could also inhibit the binding between streptavidin and biotin. Likewise, L‐peptides selected from a library screened with streptavidin, could inhibit the binding of both streptavidin and avidin to immobilized biotin. Furthermore, the D‐peptide, VFSVQSGS, as well as biotin could inhibit binding of streptavidin to an immobilized L‐peptide (RYHPQSGS). This indicates that the biotin‐like structure mimicked by these two seemingly very different peptides may react with the same binding sites in the streptavidin molecule.
Characterization of the conformational domains of bradykinin by computational methods
Authors: Perez Juan J. , Sanchez Yolanda M. , Centeno Nuria B.
Published: May 2005

The AMBER 4.0 force field was used to perform a characterization of the conformational profile of the nonapeptide bradykinin. A thorough conformational search was carried out using molecular dynamics as sampling technique, by computing cycles of high (900 K) and low (300 K) temperature trajectories. A total of 2400 minima were generated and subsequently clustered using the root‐mean‐square of the backbone dihedral angles as criterium. After the use of a tolerance value of 20deg;, the conformations were clustered in 233 unique conformations with energies up to 40 kcal/mol above the lowest minimum. The analysis of the low‐energy conformations indicate that the peptide exhibits a high tendency to adopt a β‐turn at the C‐terminus and a propensity to adopt a bent structure at the N‐terminus. These results are in agreement with the experimental evidence reported in the literature and provide detailed information necessary to understand the conformational preferences of the peptide.
Conformational rigidity versus flexibility in a novel peptidic neurokinin A receptor antagonist
Authors: Pavone Vincenzo , Lombardi Angelina , Maggi Carlo Alberto , Quartara Laura , Pedone Carlo
Published: May 2005

Neurokinin A receptor antagonists have been proposed as a new class of drugs for several applications in humans (asthama, intestinal motility, etc.). The rational design, synthesis, structural characterization and biological activity evaluation of a new potent, highly selective, long‐lasting, peptide‐based receptor antagonist are reported. The structure–activity relationship indicates that the conformational rigidity determines potency, specificity and especially the long life of the molecule in the living body. MEN 10627 is the prototype of a new class of cyclic, peptide‐based, neurokinin A receptor antagonists and it is a suitable candidate for clinical testing in humans.
Solution versus solid‐phase cyclization strategies for large sidechain lactam‐bridged peptides: A comparative study
Authors: Camarero Julio A. , Cairó Jordi J. , Giralt Ernest , Andreu David
Published: May 2005

A 22‐residue peptide with a sidechain lactam bridge involving 18 residues (60‐atom cycle) has been synthesized. Three different protection schemes using Fmoc/tBu/cyclohexyl, Fmoc/tBu/allyl or Boc/Bzl/ fluorenylmethyl protecting group combinations have been explored for the solid phase of the linear precursors, which have been subsequently cyclized in solution or in the solid phase. Cyclization yields in solution have been consistently better than on solid phase; however, the solid‐phase strategy requires fewer purification steps and therefore global yields are comparable.
Conformational studies on synthetic peptides reproducing the dibasic processing site of pro‐ocytocin–neurophysin
Authors: Di Bello Carlo , Simonetti Mario , Dettin Monica , Paolillo Livio , D'Auria Gabriella , Falcigno Lucia , Saviano Michele , Scatturin Angelo , Vertuani Gianni , Cohen Paul
Published: May 2005

Synthetic peptides reproducing the proteolytic processing site of pro‐ocytocin were studied by different spectroscopic techniques, including circular dichroism, Fourier tranform infrared absorption, and mono and bidimensional nuclear magnetic resonance, in order to ascertain the possible role of three‐dimensional structure in the recognition process by maturation enzymes. Experimental results were compared with energy minimization calculations and suggest that: (i) the region situated on the N‐terminus of the Lys‐Arg doublet may form a β‐turn; (ii) the sequential organization of the residues participating in the β‐turn determines the privileged relative orientation of the basic amino acid sidechains and the subtype of turn; and (iii) the peptide segment situated on the C‐terminal side of the dibasic doublet may assume a helix arrangement. These findings, in spite of the limitations connected to the flexibility of linear peptides, seem to substantiate the hypothesis that structural motifs around the cleavage site could be important for recognition and processing. However, a straightforward correlation between details of the secondary structure and the in vitro reactivity toward a putative convertase is not yet possible.
Augmentation of the affinity of HLA class I‐binding peptides lacking primary anchor residues by manipulation of the secondary anchor residues
Authors: Rovero Paolo , Viganò Stefania , Pegoraro Stefano , Revoltella Roberto , Riganelli Daniela , Fruci Doriana , Greco Giulia , Butler Richard H. , Tanigaki Nobuyuki
Published: May 2005

A direct binding assay has been used to investigate the effect of the secondary anchor residues on peptide binding to class I proteins of the major histocompatibility complex. Based on predictions from a previous chemometric approach, synthetic peptide analogues containing unnatural amino acids were synthesized and tested for B*2705 binding. Hydrophobic unnatural amino acids such as α‐naphthyl‐ and cyclohexyl‐alanine were found to be excellent substituents in the P3 secondary anchor position giving peptides with very high B*2705‐binding affinity. The binding to B*2705 of peptides optimized for their secondary anchor residues, but lacking one of the P2 or P9 primary anchor residues was also investigated. Most such peptides did not bind, but one peptide, lacking the P2 Arg residue generally considered essential for binding to all B27 subtypes, was found to bind quite strongly. These findings demonstrate that peptide binding to class I proteins is due to a combination of all the anchor residues, which may be occupied also by unnatural amino acids–a necessary step towards the development of peptidic or non‐peptidic antagonists for immunomodulation.
Lactam bridge stabilization of α‐helical peptides: Ring size, orientation and positional effects
Authors: Houston Michael E. , Gannon Cindy L. , Kay Cyril M. , Hodges Robert S.
Published: May 2005

A series of 14 residue amphipathic α‐helical peptides, in which the sidechains of glutamic acid and lysine have been covalently joined, was synthesized in order to determine the effect of spacing, position and orientation of these lactam bridges. It was found that although an (i, i+3) spacing would position the lactam bridge on the same face of the helix, these lactams with 18‐member rings were actually helix‐destabilizing regardless of position or location. On the other hand, (i, i+4) lactams with 21‐member rings were helix‐stabilizing but this was dependent on orientation. Glutamic acid‐lysine lactams increased the helical content of the peptide when compared with their linear homologue in benign conditions (50 mM KH2PO4, 100 mM KCl, pH 7). Two Glu‐Lys (i, i+4) lactams located at the N‐ and C‐termini gave rise to a peptide with greater than 99% helical content in benign conditions. Peptides with Lys‐Glu oriented lactams were random structures in benign conditions but in the presence of 50% TFE could be induced into a helical conformation. The stability of the single‐stranded α‐helices, as measured by thermal denaturations in 25% TFE indicated that Glu‐Lys oriented lactam bridges stabilized the helical conformation relative to the linear unbridged peptide. One Glu‐Lys lactam in the middle of the peptide was more effective at stabilizing helical structure than two Glu‐Lys lactams positioned one at each end of the molecule. The lactams with the Lys‐Glu orientation were destabilizing relative to the unbridged peptide. This study demonstrates that correct orientation and position of a lactam bridge is critical in order to design peptides with high helical content in aqueous media.
The application of papain, ficin and clostripain in kinetically controlled peptide synthesis in frozen aqueous solutions
Authors: Hänsler Marion , Ullmann Grit , Jakubke Hans‐Dieter
Published: May 2005

The capability of the cysteine proteases ficin, papain and clostripain to form peptide bonds in frozen aqueous solutions was investigated. Freezing the reaction mixture resulted in increased peptide yields in kinetically controlled coupling of Bz–Arg–OEt with various amino acid amides and dipeptides. Under these conditions, peptide yields increased up to 70% depending on the enzyme and the amino component used. Enzyme‐catalysed peptide syntheses were carried out under optimized reaction conditions (temperature, amino component concentration and pH before freezing) using the condensation of Bz–Arg–OEt and H–Leu–NH2 as a model reaction.
Affinity purification of 101 residue rat cpn10 using a reversible biotinylated probe
Authors: Ball H. L. , Bertolini G. , Mascagni P.
Published: May 2005

The purification of large synthetic peptides using conventional separation techniques often results in poor yields and homogeneity due to the accumulation of chromatographically similar deletion and truncated impurities. We have developed a highly effective synthetic strategy and one‐step purification procedure that is based on (i) the application of single coupling using HBTU/HOBt activation to reduce incomplete couplings, (ii) the use of N‐(2‐chlorobenzyloxycarbonyloxy)succinimide as a capping agent to terminate deletion sequences and (iii) the N‐terminal derivatization of the complete peptidyl‐resin with a reversible Fmoc‐based chromatographic probe possessing enhanced physico‐chemical properties (i.e. hydrophobicity, charge or affinity label). We report the application of a biotinylated probe, activated as the succinimidyl carbonate, for the purification of a 101 residue chaperonin protein from Rattus norvegicus (rat cpn10), previously synthesized using an optimized synthetic protocol. Biotinylated rat cpn10 was separated from underivatized impurities on an immobilized monomeric avidin column. Free rat cpn10 was released from avidin–agarose column with 5% aqueous triethylamine and after desalting by RP‐HPLC gave 9.9% recovery. Characterization and assessment of homogeneity was achieved using ESI‐MS, CZE and RP‐HPLC.
The immunosuppressive mini‐domain of human lactoferrin
Authors: Siemion Ignacy Z. , Sloń Jacek , Wieczorek Zbigniew
Published: May 2005

It has been found that the disulphide‐bridged 231–245 pentadecapeptide loop of the lactoferrin (LF) N‐lobe contains a region of immunosuppressive activity. The activity resides within a thymopentin‐like sequence (Arg‐Lys‐Pro‐Val‐Asp) of the loop. Peptides related to the 575–589 loop of the LF C‐lobe differ in their immunomodulatory activity from those related to the 231–245 loop. We ascribe this difference to the replacement of the Asp residue in the 231–245 loop by Thr in the 575–589 loop. Two other fragments of LF which were studied, 27–34 and 309–315, do not manifest any activy in the DTH test (cellular immune response), but, on testing in vivo, stimulate the humoral immune response. The 27–34 fragment is related to the bactericidal and immunostimulative region of LF identified by Bellamy et al. [1]. Our results show that the LF molecule contains, not only the known immunostimulating mini‐domain, but also a region endowed with immunosuppressive activity.
Synthesis and bioactivity studies of 1‐adamantanamine derivatives of peptides
Authors: Horvat Štefica , Varga‐Defterdarovič Lidija , Horvat Jaroslav , Jukić Ruža , Kantoci Darko , Chung Nga N. , Schiller Peter W. , Biesert Lothar , Pfützner Andreas , Suhartono Haryadi , Rübsamen‐Waigmann Helga
Published: May 2005

Small enkephalin‐related peptides containing a 1‐adamantanamine moiety coupled through an amide linkage at the C‐terminus were synthesized. Several of the compounds showed high μ opioid activity and μ receptor selectivity. The new adamantanamine derivatives were also examined for antiviral activity against HIV‐1 in a cell culture system. Some of them inhibited syncytia formation even when the antigen assay gave evidence for viral replication.
Chemical synthesis of a 7 kDa insect gonadotropic neurohormone
Authors: Girardie Josiane , Girardie Adrien , Van Dorsselaer Alain , Sorokine Odile , Geoffre Serge , Hospital Michel , Precigoux Gilles
Published: May 2005

An original insect neurohormone of 65 residues was synthesized by the solid‐phase methodology using t‐Boc strategy and Boc‐Val‐PAM–resin. The purification, conducted by several steps of liquid chromatography having mass, polarity or charge as separative criteria, yielded the product with the correct molecular weight of 6922 Da determined by mass spectrometry. The synthetic peptide had both the same affinity for the antinative neurohormone serum and the same biological activity as the native neurohormone.
Relationship of sidechain hydrophobicity and α‐helical propensity on the stability of the single‐stranded amphipathic α‐helix
Authors: Monera Oscar D. , Sereda Terrance J. , Zhou Nian E. , Kay Cyril M. , Hodges Robert S.
Published: May 2005

The aim of the present investigation is to determine the effect of α‐helical propensity and sidechain hydrophobicity on the stability of amphipathic α‐helices. Accordingly, a series of 18‐residue amphipathic α‐helical peptides has been synthesized as a model system where all 20 amino acid residues were substituted on the hydrophobic face of the amphipathic α‐helix. In these experiments, all three parameters (sidechain hydrophobicity, α‐helical propensity and helix stability) were measured on the same set of peptide analogues. For these peptide analogues that differ by only one amino acid residue, there was a 0.96 kcal/mole difference in α‐helical propensity between the most (Ala) and the least (Gly) α‐helical analogue, a 12.1‐minute difference between the most (Phe) and the least (Asp) retentive analogue on the reversed‐phase column, and a 32.3°C difference in melting temperatures between the most (Leu) and the least (Asp) stable analogue. The results show that the hydrophobicity and α‐helical propensity of an amino acid sidechain are not correlated with each other, but each contributes to the stability of the amphipathic α‐helix. More importantly, the combined effects of α‐helical propensity and sidechain hydrophobicity at a ratio of about 2:1 had optimal correlation with α‐helix stability. These results suggest that both α‐helical propensity and sidechain hydrophobicity should be taken into consideration in the design of α‐helical proteins with the desired stability.
Conformational behaviour of A cyclolinopeptide a analogue: Two‐dimensional NMR study of cyclo(Pro1‐Pro‐Phe‐Phe‐Ac6c‐IIe‐ala‐Val8)
Authors: Mazzeo Marco , Isernia Carla , Rossi Filomena , Saviano Michele , Pedone Carlo , Paolillo Livio , Benedetti Ettore , Pavone Vincenzo
Published: May 2005

The cyclic octapeptide cyclo[‐Pro1‐Pro‐Phe‐Phe‐Ac6c‐Ile‐ala‐Val8‐] [C8‐Ac6c], containing the Pro1‐Pro‐Phe‐Phe sequence, followed by a bulky helicogenic Cα,α‐dialkylated glycine residue Ac6c (1‐aminocyclohexane‐1‐carboxylic acid), and a D‐Ala residue at position 7 has been synthesized. This cyclic peptide is a deletion analogue of the naturally occurring cyclic nonapeptide cyclolinopeptide A (CLA). It has been designed with the aim of studying the role that the Ac6c and D‐Ala residues play on the conformational behaviour of the whole molecule and their influence on the conformation of the Pro1‐Pro‐Phe‐Phe sequence when compared with cyclolinopeptide A.

C8Ac6c has been investigated in chloroform and acetonitrile solutions by 2D NMR techniques. Only one set of sharp signals is observed in both solvents. This evidence strongly supports the hypothesis that only one conformational state exists in the chosen solvents. The interpretation of the experimental data points to the existence for C8‐Ac6c of a very rigid structure stabilized by intramolecular hydrogen bonds. The measured NOE effects allow the calculation of internuclear distances, which have been used as restraints in molecular dynamic calculations. The proposed conformation of the molecule shows that the Pro‐Pro‐Phe segment retains the conformation observed in natural CLA both in solution and in the solid state and that the Ac6c residue indeed reinforces the ring rigidity not permitting the formation of any appropriate cavity in which inorganic cations could be complexed.