摘要:

AbstractNonenzymatic glycation of proteins, peptides and other macromolecules (the Maillard reaction) has been implicated in a number of pathologies, most clearly in diabetes mellitus, but also in the normal processes of aging and neurodegenerative amyloid diseases such as Alzheimer's. In the early stage, glycation results in the formation of Amadori‐modified proteins. In the later stages, advanced glycation end products (AGE) are irreversibly formed from Amadori products leading to the formation of reactive intermediates, crosslinking of proteins, and the formation of brown and fluorescent polymeric materials. Although, the glycation of structural proteins has been attributed a key role in the complications of diabetes, recent attention has been devoted to the physiological significance of glycated peptide hormones. This review focuses on the physico‐chemical properties of the Amadori compounds of bioactive peptides of endogenous and exogenous origin, such as Leu‐enkephalin and morphiceptin, investigated under different conditions as well as on novel pathways in the Maillard reaction observed from investigating intramolecular events in ester‐linked glycopeptides. Copyright © 2003 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.519

出版商:John Wiley&Sons, Ltd.    

年代:2004

数据来源: WILEY

摘要:

AbstractThe complete primary structure of the A chain of mistletoe lectin III (ML3A), a type II ribosome‐inactivating protein, was determined using proteolytic digests of ML3A, HPLC separation of the peptides, Edman degration and MALDI‐MS. Based on our results, ML3A consists of 254 amino acid residues, showing a high homology to the A chain of isolectin ML1 with only 24 amino acid residue exchanges. A striking important structural difference compared with ML1A is the lack of the single N‐glycosylation site in ML3A due to an amino acid exchange at position 112 (ML1A: N112GS↠ML3A: T112GS). The alignment of ML3A with the A chains of ML1, isoabrins, ricin D,Ricinus communisagglutinin and three lectins, identified from the Korean mistletoeViscum albumssp.coloratum, demonstrates the rigid conservation of all amino acid residues, responsible for the RNA‐N‐glycosidase activity as reported for ricin D. In addition, the fully determined primary structure of ML3A will give further information about the biological mechanism of mistletoe lectin therapy. Copyright © 2003 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.505

出版商:John Wiley&Sons, Ltd.    

年代:2004

数据来源: WILEY

摘要:

Abstractα‐Aminoisobutyric acid (Aib), one of the Cα, α‐disubstituted glycines, is a sterically hindered amino acid that acts as a conformational constraint in peptides. However, studies for the application of the ability of Aib to control conformation are quite few. The paper focuses on the molecular recognition ability of acyclic oligopeptides containing Aib. Liquid–liquid extraction of nine kinds of metal ions from aqueous layers to nonpolar organic layers with acyclic tetrapeptides, X‐Trp‐Xaa2‐Gly‐Xaa4‐NH‐Ar (X = H or C6H5CH2OCO (Z), Xaa2= Aib or Gly, Xaa4= Leu or Ala, Ar = phenyl or 3,5‐dimethylphenyl) was examined using picrate as the anion of ion pairs. The extraction behaviour of the metal ions with the tetrapeptides was investigated in the pH range from 3 to 9. In the case of basic pH regions, Cu(II) and Ag(I) were effectively extracted with Trp‐Aib‐Gly‐Leu‐NH‐Ar. Pd(II) was specifically extracted with Trp‐Aib‐Gly‐Leu‐NH‐Ar in acidic pH regions. The extraction percent (%E) of the peptide host, which has a 3,5‐dimethylphenyl group, was even larger than that of the host, which has a phenyl group. Moreover, Pd(II) was extracted with a peptide host which has Leu and a 3,5‐dimethylphenyl group in the absence of picrate as the anion of ion pairs. The free α‐amino group, the turn conformation and the hydrophobicity of peptide molecules were important factors for the extraction of the metals. Copyright © 2003

ISSN:1075-2617    

DOI:10.1002/psc.538

出版商:John Wiley&Sons, Ltd.    

年代:2004

数据来源: WILEY

摘要:

AbstractA pentapeptide, Boc‐Leu‐Ac8c‐Ala‐Leu‐Ac8c‐OMe1, an octapeptide, Boc‐Leu‐Ac8c‐Ala‐Leu‐Ac8c‐Ala‐Leu‐Ac8c‐OMe2and a tripeptide, Boc‐Aib‐Ac8c‐Aib‐OMe3containing the 1‐aminocyclooctane‐1‐carboxylic acid residue (Ac8c) were synthesized and conformationally characterized by x‐ray diffraction studies in the crystal state. Peptides1and2were also studied by NMR in CDCl3solution. Peptide1adopts a purely 310‐helical conformation in crystals, stabilized by three intramolecular 1 ← 4 hydrogen bonds. Peptide2in crystals is largely 310‐helical with distortion in the backbone at theN‐terminus by the insertion of a water molecule between Ac8c (2) CO and Ala (6) NH groups. Peptide3forms a C10‐ring structure, i.e. a type III (III′) β‐ turn conformation stabilized by an intramolecular 1 ← 4 hydrogen bond. Five cyclooctane rings assume boat–chair conformations, whereas the sixth [Ac8c(8) in2] is appreciably distorted, resembling a chiral intermediate in the pseudorotational pathway from the boat–chair to the twisted boat–chair conformation. Internal bond angles of the cyclooctane rings are appreciably distorted from the tetrahedral value, a characteristic feature of the cyclooctane ring. Peptide1crystallized in the space group P212121witha= 11.900(4) Å,b= 18.728(6) Å,c= 20.471(3) Å andZ= 4. The finalR1and wR2values are 0.0753 and 0.2107, respectively, for 3901 observed reflections [Fo≥ 3σ(Fo)]. Peptide2crystallized in space group P21witha= 12.961(5) Å,b= 17.710(10) Å,c= 15.101(7) Å, β = 108.45(4)° andZ= 2. The finalR1and wR2values are 0.0906 and 0.1832, respectively, for 2743 observed reflections [Fo≥ 3σ(Fo)].1H‐NMR studies on both the peptides strongly suggest the persistence of 310‐helical conformations in solution. Peptide3crystallized in the space group P21/n, witha= 10.018(1) Å,b= 20.725(1) Å,c= 12.915(1) Å andZ= 4. The finalR1and wR2values are 0.0411 and 0.1105, respectively, for 3634 observed ref

ISSN:1075-2617    

DOI:10.1002/psc.507

出版商:John Wiley&Sons, Ltd.    

年代:2004

数据来源: WILEY

摘要:

AbstractFrom the bulbs of the onionAllium cepa, a novel antifungal peptide distinct from the antimicrobial peptide previously reported from onion seeds was isolated. The antifungal peptide, designated allicepin, was purified with a procedure that involved aqueous extraction, ion exchange chromatography on DEAE‐cellulose, affinity chromatography on Affi‐gel blue gel and FPLC‐gel filtration on Superdex 75. Allicepin was unadsorbed on DEAE‐cellulose and adsorbed on Affi‐gel blue gel. The molecular weight of allicepin was estimated to be 10 K by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and gel filtration on Superdex 75. Allicepin exerted an inhibitory activity on mycelial growth in several fungal species includingBotrytis cinerea,Fusarium oxysporum,Mycosphaerella arachidicolaandPhysalospora piricola.Copyright © 2003 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.509

出版商:John Wiley&Sons, Ltd.    

年代:2004

数据来源: WILEY