摘要:

AbstractThe potential of carbohydrate‐like tetrahydrofuran frameworks as building blocks with predictable conformational propensities useful in the design and synthesis of novel peptidomimetic materials which adopt well‐defined secondary structures is discussed. Copyright © 1999 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199910)5:10<425::AID-PSC222>3.0.CO;2-O

出版商:John Wiley&Sons, Ltd.    

年代:1999

数据来源: WILEY

摘要:

AbstractAn increased degree of utilization of the potentialN‐glycosylation site in the fourth repeat unit of the human τ protein may be involved in the inability of τ to bind to the corresponding tubulin sequence(s) and in the subsequent development of the paired helical filaments of Alzheimer's disease. To model these processes, we synthesized the octadecapeptide spanning this region without sugar, and with the addition of anN‐acetyl‐glucosamine moiety. The carbohydrate‐protected, glycosylated asparagine was incorporated as a building block during conventional Fmoc‐solid phase peptide synthesis. While the crude non‐glycosylated analog was obtained as a single peptide, two peptides with the identical, expected masses, in approximately equal amounts, were detected after the cleavage of the peracetylated glycopeptide. Surprisingly, the two glycopeptides switched positions on the reversed‐phase high performance liquid chromatogram after removal of the sugar‐protecting acetyl groups. Nuclear magnetic resonance spectroscopy and peptide sequencing identified the more hydrophobic deprotected peak as the target peptide, and the more hydrophilic deprotected peak as a peptide analog in which the aspartic acid‐bond just preceding the glycosylated asparagine residue was isomerized resulting in the formation of a β‐peptide. The anomalous chromatographic behavior of the acetylated β‐isomer could be explained on the basis of the generation of an extended hydrophobic surface which is not present in any of the other three glycopeptide variants. Repetition of the syntheses, with altered conditions and reagents, revealed reproducibly high levels of aspartic acid‐bond isomerization of the glycopeptide as well as lack of isomerization for the non‐glycosylated parent analog. If similar increased aspartic acid‐bond isomerization occursin vivo, a protein modification well known to take place for both the amyloid deposits and the neurofibrillary tangles in Alzheimer's disease, this process may explain the aggregation of glycosylated τ into the paired helical filaments in the affected brains. Copyright © 1999 European Peptide

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199910)5:10<442::AID-PSC214>3.0.CO;2-Q

出版商:John Wiley&Sons, Ltd.    

年代:1999

数据来源: WILEY

摘要:

AbstractSyntheses of several Trp‐containing peptides on a Wang solid support afforded significant amounts of a side‐product.1H‐NMR and MS data showed that an unexpected alkylation by the linker has occurred on the indole nucleus. This was observed whatever the scavenger used, and whatever the position of the Trp residue in the sequence, unless it was in theC‐terminal position. Copyright © 1999 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199910)5:10<457::AID-PSC215>3.0.CO;2-7

出版商:John Wiley&Sons, Ltd.    

年代:1999

数据来源: WILEY

摘要:

AbstractThe original article to which this Erratum refers was published in Journal of Peptide Science 1999;5: 283–28

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199910)5:10<462::AID-PSC234>3.0.CO;2-M

出版商:John Wiley&Sons, Ltd.    

年代:1999

数据来源: WILEY