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  • 1
    Electronic Resource
    Electronic Resource
    Base-induced side reactions in Fmoc-solid phase peptide synthesis: Minimization by use of piperazine as Nα-deprotection reagent (2000)
    Springer
    International journal of peptide research and therapeutics 7 (2000), S. 107-112 
    Details
    ISSN: 1573-3904
    Keywords: aspartimide formation ; base-induced side reaction ; Fmoc-solid phase peptide synthesis ; Nα-deprotection reagent ; piperazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Base-induced aspartimide (cyclic imide) and subsequent base adduct formation in the Fmoc-solid phase synthesis of sensitive sequences are serious side reactions that are difficult to both anticipate and control. The effect of extended treatment of piperazine as Nα-Fmoc deprotection reagent on two sensitive peptide sequences was examined. For comparison, other bases were also investigated, including piperidine, 1-hydroxypiperidine, tetrabutylammonium fluoride, and 1,8-diazabicyclo[5.4.0]undec-7-ene. The results showed that all bases induced varying degrees of both aspartimide and, in some cases, base adduct formation, although piperazine caused the least side reaction. Use ofN-(2-hydroxy-4-methoxybenzyl) peptide backbone amide protection was confirmed to confer complete protection against side reaction. In the absence of such protection, for all bases, the use of 1-hydroxybenzotriazole as additive had some, but not complete, beneficial effect in further reducing side reaction. Best results were obtained with piperazine containing 0.1M 1-hydroxybenzotriazole indicating that this reagent merits serious consideration for Nα-deprotection in the Fmoc-solid phase synthesis of base-sensitive sequences. A further advantage of this reagent is that it causes little racemisation of resin-bound C-terminal cysteine, an occasionally serious base-mediated problem in Fmoc-solid phase assembly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443569
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and conformational analysis of an O-phosphotyrosine-containing α-helical peptide (1995)
    Springer
    International journal of peptide research and therapeutics 2 (1995), S. 71-76 
    Details
    ISSN: 1573-3904
    Keywords: Circular dichroism spectroscopy ; Peptide conformation ; O-phosphotyrosine peptide ; Solid-phase peptide synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The continuous-flow Fmoc solid-phase synthesis methodology was used together with the derivative Fmoc-Tyr(PO3Bzl2)-OH to successfully prepare an O-phosphorylated tyrosine analogue of a heptadecapeptide which was designed to adopt an α-helical conformation in solution. Comprehensive chemical characterization, including ion-spray mass spectrometry, confirmed the high purity of the synthetic peptide and the presence of the tyrosine O-phosphate moiety. Circular dichroism spectroscopic analysis showed that, in water and at low concentration, the peptide has a greater degree of helicity or possibly a longer helix chain length than the non-O-phosphorylated form. A similar phenomenon was observed in the membrane-mimicking solvent octyl β-glucoside. The increase in the helicity during trifluoroethanol titration and the absence of apparent coiled coil-type aggregation further demonstrated the intrinsic ability of the peptides to form α-helices. The data, taken together, indicate that, at least for this peptide, the α-helix secondary structural element is more pronounced following tyrosine O-phosphorylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00128500
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Base-induced side reactions in Fmoc-solid phase peptide synthesis:Minimization by use of piperazine as Nα-deprotectionreagent (2000)
    Springer
    International journal of peptide research and therapeutics 7 (2000), S. 107-112 
    Details
    ISSN: 1573-3904
    Keywords: aspartimide formation ; base-induced side reaction ; Fmoc-solid phase peptide synthesis ; Nα-deprotection reagent ; piperazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Base-induced aspartimide (cyclic imide) and subsequentbase adduct formation in the Fmoc-solid phasesynthesis of sensitive sequences are serious sidereactions that are difficult to both anticipate andcontrol. The effect of extended treatment ofpiperazine as Nα-Fmoc deprotection reagenton two sensitive peptide sequences was examined. Forcomparison, other bases were also investigated,including piperidine, 1-hydroxypiperidine,tetrabutylammonium fluoride, and1,8-diazabicyclo[5.4.0]undec-7-ene. The results showedthat all bases induced varying degrees of bothaspartimide and, in some cases, base adduct formation,although piperazine caused the least side reaction.Use of N-(2-hydroxy-4-methoxybenzyl) peptidebackbone amide protection was confirmed to confercomplete protection against side reaction. In theabsence of such protection, for all bases, the use of1-hydroxybenzotriazole as additive had some, but notcomplete, beneficial effect in further reducing sidereaction. Best results were obtained with piperazinecontaining 0.1M 1-hydroxybenzotriazole indicating thatthis reagent merits serious consideration forNα-deprotection in the Fmoc-solid phasesynthesis of base-sensitive sequences. A furtheradvantage of this reagent is that it causes littleracemisation of resin-bound C-terminal cysteine, anoccasionally serious base-mediated problem in Fmoc-solidphase assembly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008966207751
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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