摘要:

Subcutaneous injections of insulin remain the standard treatment for insulin‐dependent diabetic patients, and noninvasive routes are studied but with little success. One of the reasons is that insulin is a hydrophilic compounds and is difficult to cross the mucosa barrier. In this paper, we developed a novel technique to fabricate the insulin–phospholipids complex by a solvent evaporation method with the aim of improving the lipophilicity of insulin. A systematic study on the preparation conditions of the insulin–phospholipids complex is reported in the present work. The formation mechanism and the physicochemical properties of the complex are studied. The associated efficiency of the phospholipids and insulin can be up to 100% when their mass ratio is 7.5 : 1 or more, and the solubility of the complex is improved more than 40 000 times compared with that of insulin alone in then‐octyl alcohol. The results of the insulin content in the complex and hypoglycemic effects in diabetic mice indicated that insulin was able to withstand the preparation procedure. The stability results showed that the complex was stable for 1 year at −20 °C. The interaction mechanism of this formation is that the peptide bonds of insulin interact with the water‐soluble head of phospholipids, forming a reverse micelle‐like structure. This novel complex will be of great importance in the drug delivery system for insulin via noninvasive routes. This method is cost effective, scalable, and can be used in many other peptide drugs. Copyright © 2012 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.2423

出版商:John Wiley&Sons, Ltd    

年代:2012

数据来源: WILEY

摘要:

Unquestionably, the purification of polypeptides by chromatographic methods is a considerable bottleneck in their preparation. Peptides synthesised by solid phase synthesis typically contain chromatographically similar impurities that complicate purification by reversed phase high performance liquid chromatography (HPLC) techniques. We report on the application of a slow gradient HPLC protocol that allows, in a single chromatographic step, the purification of hundreds of milligrammes of material. This technique was applied to an extensive collection of synthetic polypeptides some incorporating non‐proteinogenic functionality. In all cases examined, the peptides were not only obtained in high purity peptides but were also recovered in multi‐milligramme amounts. Copyright © 2012 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.2432

年代:2012

数据来源: WILEY

摘要:

β‐Amino acids containing α,β‐hybrid peptides show great potential as peptidomimetics. In this paper, we describe the synthesis and affinity to μ‐opioid and δ‐opioid receptors of α,β‐hybrids, analogs of the tetrapeptide Tyr‐d‐Ala‐Phe‐Phe‐NH2(TAPP). Each amino acid was replaced with anl‐ ord‐β3‐h‐amino acid. All α,β‐hybrids of TAPP analogs were synthesized in solution and tested for affinity to μ‐opioid and δ‐opioid receptors. The analog Tyr‐β3h‐d‐Ala‐Phe‐PheNH2was found to be as active as the native tetrapeptide. Copyright

ISSN:1075-2617    

DOI:10.1002/psc.2433

年代:2012

数据来源: WILEY

摘要:

LL37 and histatin 5 are antimicrobial peptides. LL37 exhibits killing activity against a broad spectrum of pathogens, whereas histatin 5 is primarily an antifungal agent. Head‐to‐tail cyclization of histatin 5 did not affect its antimicrobial and haemolytic activity. The cyclic LL37 exhibits identical antifungal and haemolytic activity as does LL37. Its antimicrobial activity varied in one dilution depending on the kind of bacteria. The structure of cyclic peptides was studied by circular dichroism spectroscopy. Both peptides undergo a conformational change leading to stabilisation of theirα‐helical structure in the presence of negatively charged sodium dodecyl sulfate micelles. However, with cyclic histatin 5, the presence of Zn2+ions is also necessary to fuse the peptide to the micelle. The specific action of the Zn2+ions is attributed to the presence of a zinc‐binding motif, His‐Glu‐X‐X‐His. It has been speculated that this zinc complexing may be related to the well‐established anticandidal activity. In the case of cyclic LL37, also the presence of a zwitterionic dodecylphosphocholine micelle induces formation of the helical structure. A microwave‐assisted procedure for the cleavage of a peptide from the 2‐chlorotrityl chloride resin was, for the first time, successfully used to obtain protected peptide fragments that can be applied to the preparation of head‐to‐tail cyclopeptides or to condensation of peptidic fragments. Copyright © 2012 European Peptide Socie

ISSN:1075-2617    

DOI:10.1002/psc.2434

年代:2012

数据来源: WILEY

摘要:

Worldwide efforts are underway to develop new antimicrobial agents against bacterial resistance. To identify new compounds with a good antimicrobial profile, we designed and synthesized two series of small cationic antimicrobial peptidomimetics (1–8) containing unusual arginine mimetics (to introduce cationic charges) and several aromatic amino acids (bulky moieties to improve lipophilicity). Both series were screened forin vitroantibacterial activity against a representative panel of Gram‐positive (Staphylococcus aureusandStaphylococcus epidermidis) and Gram‐negative (Escherichia coliandKlebsiella pneumoniae) bacterial strains, andCandida albicans. The biological screening showed that peptidomimetics containing tryptophan residues are endowed with the best antimicrobial activity againstS. aureusandS. epidermidisin respect to the other synthesized derivatives (MIC values range 7.5–50 µg/ml). Moreover, small antimicrobial peptidomimetics derivatives 2 and 5 showed an appreciable activity against the tested Gram‐negative bacteria andC. albicans. The most active compounds (1–2 and 5–6) have been tested against Gram‐positive established biofilm, too. Results showed that the biofilm inhibitory concentration values of these compounds were never up to 200 µg/ml. The replacement of tryptophan with phenylalanine or tyrosine resulted in considerable loss of the antibacterial action (compounds 3–4 and 7–8) against both Gram‐positive and Gram‐negative bacterial strains. Furthermore, by evaluating hemolytic activity, the synthesized compounds did not reveal cytotoxic activities, except for compound 5. Copyright © 2012 European Peptide So

ISSN:1075-2617    

DOI:10.1002/psc.2435

年代:2012

数据来源: WILEY

摘要:

It has been hypothesized that amphipathic peptides might bind to membranes prior to activating their cognate receptors, but this has proven difficult to test. The peptide hormone PYY3‐36 is believed to perform its appetite‐suppressing actions through binding to hypothalamic Y2 receptors. It has been proposed that PYY3‐36 via its amphipathic α‐helix binds to the plasma membrane prior to receptor docking. Here, our aim was to study the implication of this hypothesis using new analogs of PYY3‐36. We first studied membrane binding of PYY3‐36. Next, we designed a series of PYY3‐36 analogs to increase membrane‐binding affinity by substituting theN‐terminal segment with ade novodesigned α‐helical, amphipathic sequence. These 2‐helix variants of PYY3‐36 were assembled by solid‐phase peptide synthesis. Pharmacological studies demonstrated that even though the native peptide sequence was radically changed, highly active Y2 receptor agonists were generated. A potent analog, with a Kd of 4 nM for membranes, was structurally characterized by NMR in the membrane‐bound state, which clearly showed that it formed the expected 2‐helix. The topology of the peptide–micelle association was studied by paramagnetic relaxation enhancement using a spin label, which confirmed that the hydrophobic residues bound to the membrane. Our studies further support the hypothesis that PYY3‐36 associates with the membrane and indicate that this can be used in the design of novel molecules with high receptor binding potency. These observations are likely to be generally important for peptide hormones and biopharmaceutical drugs derived from them. This new 2‐helix variant of PYY3‐36 will be useful as a tool compound for studying peptide–membrane interactions. Copyright © 2012 Europ

ISSN:1075-2617    

DOI:10.1002/psc.2436

年代:2012

数据来源: WILEY

摘要:

Gomesin (Gm) was the first antimicrobial peptide (AMP) isolated from the hemocytes of a spider, the Brazilian mygalomorphAcanthoscurria gomesiana. We have been studying the properties of this interesting AMP, which also displays anticancer, antimalarial, anticryptococcal and anti‐Leishmaniaactivities. In the present study, the total syntheses of backbone‐cyclized analogues ofGm(two disulfide bonds), [Cys(Acm)2,15]‐Gm(one disulfide bond) and [Thr2,6,11,15,d‐Pro9]‐Gm(no disulfide bonds) were accomplished, and the impact of cyclization on their properties was examined. The consequence of simultaneous deletion of pGlu1and Arg16‐Glu‐Arg18‐NH2onGmantimicrobial activity and structure was also analyzed. The results obtained showed that the synthetic route that includes peptide backbone cyclization on resin was advantageous and that a combination of 20% DMSO/NMP, EDC/HOBt, 60 °C and conventional heating appears to be particularly suitable for backbone cyclization of bioactive peptides. The biological properties of theGmanalogues clearly revealed that the N‐terminal amino acid pGlu1and the amidated C‐terminal tripeptide Arg16‐Glu‐Arg18‐NH2play a major role in the interaction ofGmwith the target membranes. Moreover, backbone cyclization practically did not affect the stability of the peptides in human serum; it also did not affect or enhanced hemolytic activity, but induced selectivity and, in some cases, discrete enhancements of antimicrobial activity and salt tolerance. Because of its high therapeutic index, easy synthesis and lower cost, the [Thr2,6,11,15,d‐Pro9]‐Gmanalogue remains the best activeGm‐derived AMP developed so far; nevertheless, its elevated instability in human serum may limit its therapeutic potential. Copyright © 2012 European Pepti

ISSN:1075-2617    

DOI:10.1002/psc.2439

年代:2012

数据来源: WILEY