ISSN:1075-2617    

DOI:10.1002/psc.304

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractAlthough peptides themselves are not usually the end products of a drug discovery effort, peptide research often plays a key role in many aspects of this process. This will be illustrated by reviewing the experience of peptide research carried out at IRBM in the course of our study of hepatitis C virus (HCV). The target of our work is the NS3/4A protease, which is essential for maturation of the viral polyprotein. After a thorough examination of its substrate specificity we fine‐tuned several substrate‐derived peptides for enzymology studies, high‐throughput screening and as fluorescent probes for secondary binding assays. In the course of these studies we made the key observation: that the protease is inhibited by its own cleavage products. Single analog and combinatorial optimization then derived potent peptide inhibitors. The crucial role of the NS4A cofactor was also addressed. NS4A is a small transmembrane protein, whose central domain is the minimal region sufficient for enzyme activation. Structural studies were performed with a peptide corresponding to the minimal activation domain, with a series of product inhibitors and with both. We found that NS3/4A is an induced fit enzyme, requiring both the cofactorandthe substrate to acquire its bioactive conformation; this explained some puzzling results of ‘serine‐trap’ type inhibitors. A more complete study on NS3 activation, however, requires the availability of the full‐length NS4A protein. This was prepared by native chemical ligation, after sequence engineering to enhance its solubility; structural studies are in progress. Current work is focused on the P′ region of the substrate, which, at variance with the P region, is not used for ground state binding to the enzyme and might give rise to inhibitors showing novel interactions with the enzyme. Copyright © 2001 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.310

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractSecondary structure formation and stability are essential features in the knowledge of complex folding topology of biomolecules. To better understand the relationships between preferred conformations and functional properties of β‐homo‐amino acids, the synthesis and conformational characterization by X‐ray diffraction analysis of peptides containing conformationally constrained Cα,α‐dialkylated amino acid residues, such as α‐aminoisobutyric acid or 1‐aminocyclohexane‐1‐carboxylic acid and a single β‐homo‐amino acid, differently displaced along the peptide sequence have been carried out. The peptides investigated are: Boc‐βHLeu‐(Ac6c)2‐OMe, Boc‐Ac6c‐βHLeu‐(Ac6c)2‐OMe and Boc‐βHVal‐(Aib)5‐OtBu, together with theC‐protected β‐homo‐residue HCl·H‐βHVal‐OMe. The results indicate that the insertion of a βH‐residue at position 1 or 2 of peptides containing strong helix‐inducing, bulky Cα,α‐disubstituted amino acid residues does not induce any specific conformational preferences. In the crystal state, most of the NH groups of β‐homoresidues of tri‐ and tetrapeptides are not involved in intramolecular hydrogen bonds, thus failing to achieve helical structures similar to those of peptides exclusively constituted of Cα,α‐disubstituted amino acid residues. However, by repeating the structural motifs observed in the molecules investigated, a β‐pleated sheet secondary structure, and a new helical structure, named (14/15)‐helix, were generated, corresponding to calculated minimum‐energy conformations. Our findings, as well as literature data, strongly indicate that conformations of βH‐residues, with theµtorsion angle equal to

ISSN:1075-2617    

DOI:10.1002/psc.278

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractQuinolones constitute a family of compounds with a potent antibiotic activity. The enzyme DNA gyrase, responsible for the replication and transcription processes in DNA of bacteria, is involved in the mechanism of action of these drugs. In this sense, it is believed that quinolones stabilize the so‐called ‘cleavable complex’ formed by DNA and gyrase, but the whole process is still far from being understood at the molecular level. This information is crucial in order to design new biological active products. As an approach to the problem, we have designed and synthesized low molecular weight peptide mimics of DNA gyrase. These peptides correspond to sequences of the subunit A of the enzyme fromEscherichia coli,that include the quinolone resistance‐determining region (positions 75–92) and a segment containing the catalytic Tyr‐122 (positions 116–130). The peptide mimic of the non‐mutated enzyme binds to ciprofloxin (CFX) only when DNA and Mg2+were present (Kd=1.6×10−6

ISSN:1075-2617    

DOI:10.1002/psc.292

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractThe primary amphipathic peptide Ac‐Met‐Gly‐Leu‐Gly‐Leu‐Trp‐Leu‐Leu‐Val‐Leu10‐Ala‐Ala‐Ala‐Leu‐Gln‐Gly‐Ala‐Lys‐Lys‐Lys20‐Arg‐Lys‐Val‐NH‐CH2‐CH2‐SH called SPM was able to induce formation of ion channels into planar lipid bilayers with main conductance values of 75 and 950 pS in 1

ISSN:1075-2617    

DOI:10.1002/psc.293

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractWe examined the potential immobilization of horseradish peroxidase (HRP) to cellulose with cellulose‐binding domain (CBD) as a mediator, using a ligand selected from a phage‐displayed random peptide library. A 15‐mer random peptide library was panned on cellulose‐coated plates covered with CBD in order to find a peptide that binds to CBD in its bound form. The sequence I/LHS, which was found to be an efficient binder of CBD, was fused to a synthetic gene of HRP as an affinity tag. The tagged enzyme (tHRP) was then immobilized on microcrystalline cellulose coated with CBD, thereby demonstrating the indirect immobilization of a protein to cellulose via three amino acids selected by phage display library and CBD. Copyright © 2001 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.294

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractIt seems likely that the β‐amyloid precursor protein (APP) and the presenilins (PS‐1/2) play important roles in the development of Alzheimer's disease (AD). Attempts to mimic the biochemical actions of these proteins are often made by the application of fragments of these proteins. However, the synthesis of these segments by conventional methods of peptide synthesis is problematic. We have synthesized severalC‐terminal fragments of APP and PS‐1/2 by solid‐phase synthesis through combination of automatic and manual methods of synthesis. This permits solution of the ‘difficult sequences’ in the solid‐phase synthesis of these peptides. Some details of the syntheses of nine segments are presented in this paper. Copyright © 2001 European Peptide Society and Joh

ISSN:1075-2617    

DOI:10.1002/psc.305

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY