A convenient and rapid method for the selective oxygen-17 enrichment of aspartyl peptides during solid-phase synthesis (original) (raw)
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Journal of Peptide Science, 2008
The sequence-dependent, acid- or base-catalysed aspartimide formation is one of the most serious side reactions in solid-phase synthesis of peptides containing aspartic acid. In the present work, we investigated the susceptibility of 4-{N-[1-(4,4-dimethyl-2,6-dioxocyclohexylidene)-3-methylbutyl]amino}benzyl (Dmab), an aspartic acid β-carboxy side-chain protecting group, for aspartimide formation. As a model, 15-amino acid-residue galanin fragment analogue containing the Asp-Ala motif was used during Fmoc-based solid-phase synthesis. Our study showed a strong tendency of Dmab-protected peptide to form aspartimide with unusual high efficiency. Furthermore, to investigate the susceptibility of Asp-Ala motif for aspartimide formation during the synthesis using Asp(ODmab), a 5-amino acid-residue galanin fragment LGPDA, different types of resin linkers, variety of Fmoc-deprotection conditions and coupling methods were applied. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis of aspartimide-free protected peptides on base-labile functionalized resins
Tetrahedron Letters, 2000
Aspartimide prone sequence containing protected peptides are successfully synthesized in solid phase by using the bifunctional linker N-[(9-hydroxymethyl)-2-fluorenyl] succinamic acid (HMFS) in combination with morpholine as the cleavage reagent. Access to high purity peptide synthons opens a straightforward way to the synthesis of large proteins by convergent strategies.
Tetrahedron Letters, 2006
We developed an efficient, cost effective strategy for Fmoc-based solid phase synthesis of 'difficult' peptides and/or peptides containing Asp/Asn-Gly sequences, free of aspartimide and related products, using a peptoid methodology for the preparation of N-substituted glycines. Alternative solutions were proposed, such as (i) Na-protecting group, 19 and (ii) linkers for SPPS of protected peptides, both cleavable under almost neutral conditions, 20 and finally, (iii) linkers cleavable with reagents less basic than PIP. 21 Tetrahedron Letters 47
ACS Omega
An efficient, convenient, and selective Lewis acid-based strategy for on-resin deprotection of the side chain tert-butyl-protected aspartic acid and glutamic acid of a peptide is achieved. The method is mild, cost-effective, and Fmoc chemistry compatible and allows on-resin incorporation of amides, esters, and thioesters in good yield. This method will find wide applicability in peptide and protein modification because it enriches the toolbox of orthogonal protection/deprotection techniques.
Cyclohexyloxycarbonyl based orthogonal solid phase peptide synthesis in Boc chemistry
Tetrahedron, 1998
Application of N-cyclohex'yloxTcafoonyl (Choc) protection in Boc chemistry on solid phase provides a new possibility for the preparation of protected peptide fragments. A Choc/OcHex protection scheme allows also the assembly of cyclic lactam peptides linked to the resin through the C-terminus. Choc protection is stable under the 1M TMSOTf-thioanisole/TFA cleavage condition at 0°C, but it is removable by anhydrous HF. We have utilized cyclohexTloxycarbonyl as an orthogonal protecting group for the synthesis of a i) bicyclic epitope peptide of glycoprotein D of HSV 1 on BHA resin and ii) fully protected hexapeptide involved in protein transport on Merrifield resin.
Rapid solid phase synthesis and biodistribution of 18F-labelled linear peptides
European Journal of Nuclear Medicine and Molecular Imaging, 2002
A rapid method for radiolabelling short peptides with 18 F (t 1/2 =109.7 min) for use in positron emission tomography (PET) was developed. Linear peptides (13mers) were synthesised using solid phase peptide synthesis and 9-fluorenylmethoxycarbonyl (Fmoc) chemistry. The peptides were assembled on a solid-phase polyethylene glycol-polystyrene support using the "hyper acid labile" linker xanthen-2-oxyvaleric acid and were labelled in situ with 4-[ 19 F]-or 4-[ 18 F]fluorobenzoic acid. Optimum coupling of 4-[ 19 F]fluorobenzoic acid to the peptidyl resin was achieved within 2 min using N-[(dimethylamino)-1H-1,2,3-triazolo[4,5-b]pyridin-1-ylmethylene]-Nmethylmethanaminium hexafluorophosphate N-oxide (HATU/DIPEA), and optimum cleavage was achieved within 7 min using trifluoroacetic acid/phenol/water/Triisopropylsilane at 37°C. The linear peptides were rapidly labelled with 4-[ 18 F]fluorobenzoic acid with an overall radiochemical yield of 80%-90% (decay corrected), a radiochemical purity of >95% without HPLC purification and an overall synthesis time of 20 min. This novel method was used to label peptides containing the arginine-glycine-aspartic acid (RGD) motif, the binding site of many integrins. In vitro studies showed that the fluorobenzoyl prosthetic group had no deleterious effect on the ability of these peptides to inhibit the binding of human cells via integrins. Biodistribution studies in tumour-bearing mice showed that although the linear peptides were rapidly removed from the circulation by the liver and kidneys, there was a transient and non-RGD-dependent accumulation in the tumour of both the test and the control peptides. The use of more selective peptides with a longer half-life in the circulation combined with this rapid labelling technique will significantly enhance the application of peptides in PET.
The Journal of Peptide Research, 2008
C-Terminal peptide aldehydes and hydroxamates comprise two separate classes of effective inhibitors of a number of serine, aspartate, cysteine, and metalloproteases. Presented here is a method for preparation of both classes of peptide derivatives from the same resin-bound Weinreb amide precursor. Thus, 5-[(2 or 4)-formyl-3,5-dimethoxyphenoxy]butyramidopolyethylene glycol-polystyrene (BAL-PEG-PS) was treated with methoxylamine hydrochloride in the presence of sodium cyanoborohydride to provide a resin-bound methoxylamine, which was efficiently acylated by different Fmoc-amino acids upon bromo-tris-pyrrolidone-phosphonium hexafluorophosphate (PyBrOP) activation. Solid-phase chain elongation gave backbone amide-linked (BAL) peptide Weinreb amides, which were cleaved either by trifluoroacetic acid (TFA) in the presence of scavengers to provide the corresponding peptide hydroxamates, or by lithium aluminum hydride in tetrahydrofuran (THF) to provide the corresponding C-terminal peptide aldehydes. With several model sequences, peptide hydroxamates were obtained in crude yields of 68-83% and initial purities of at least 85%, whereas peptide aldehydes were obtained in crude yields of 16-53% and initial purities in the range of 30-40%. Under the LiAlH 4 cleavage conditions used, those model peptides containing t-Bu-protected aspartate residues underwent partial side chain reduction to the corresponding homoserine-containing peptides. Similar results were obtained when working with high-load aminomethylpolystyrene, suggesting that this chemistry will be generally applicable to a range of supporting materials. Abbreviations: The rules of the IUPAC-IUB Commission of Biochemical Nomenclature [(1989) J. Biol. Chem. 264, 668-673] are used for amino acid and peptide abbreviations. Amino acid Dates:
Solid‐phase synthesis of C‐terminally modified peptides
Journal of Peptide …, 2006
In this paper, a straightforward and generic protocol is presented to label the C-terminus of a peptide with any desired moiety that is functionalized with a primary amine. Amine-functional molecules included are polymers (useful for hybrid polymers), long alkyl chains (used in peptide amphiphiles and stabilization of peptides), propargyl amine and azido propyl-amine (desirable for 'click' chemistry), dansyl amine (fluorescent labeling of peptides) and crown ethers (peptide switches/hybrids). In the first part of the procedure, the primary amine is attached to an aldehyde-functional resin via reductive amination. To the secondary amine that is produced, an amino acid sequence is coupled via a standard solid-phase peptide synthesis protocol. Since one procedure can be applied for any given amine-functional moiety, a robust method for C-terminal peptide labeling is obtained.
Solid-phase synthesis of C-terminal modified peptides
Biopolymers, 2003
In this paper, a straightforward and generic protocol is presented to label the C-terminus of a peptide with any desired moiety that is functionalized with a primary amine. Amine-functional molecules included are polymers (useful for hybrid polymers), long alkyl chains (used in peptide amphiphiles and stabilization of peptides), propargyl amine and azido propyl-amine (desirable for 'click' chemistry), dansyl amine (fluorescent labeling of peptides) and crown ethers (peptide switches/hybrids). In the first part of the procedure, the primary amine is attached to an aldehyde-functional resin via reductive amination. To the secondary amine that is produced, an amino acid sequence is coupled via a standard solid-phase peptide synthesis protocol. Since one procedure can be applied for any given amine-functional moiety, a robust method for C-terminal peptide labeling is obtained.