Rapid and efficient method for the preparation of Fmoc‐amino acids starting from 9‐fluorenylmethanol

Kortenaar, Paul B. W. Ten; DIJK, B. G. VAN; Peeters, J.; RAABEN, B. J.; Adams, P. J.; Tesser, G. I.

doi:10.1111/j.1399-3011.1986.tb01034.x

Cited by 105 publications

(43 citation statements)

References 8 publications

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“…Commercial L-alanine, deuterated at C ␣ and C ␤ carbons (Ala-d 4 ), from Cambridge Isotope Laboratories (Andover, MA) was derivatized with an Fmoc-protecting group as described previously (21,22). DLPC, DMPC, and DOPC were purchased from Avanti Polar Lipids (Alabaster, AL).…”

Section: Methodsmentioning

confidence: 99%

Charged or Aromatic Anchor Residue Dependence of Transmembrane Peptide Tilt

Vostrikov

Daily

Greathouse

et al. 2010

Journal of Biological Chemistry

185

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The membrane-spanning segments of integral membrane proteins often are flanked by aromatic or charged amino acid residues, which may "anchor" the transmembrane orientation. Single spanning transmembrane peptides such as those of the WALP family, acetyl-GWW(LA) n LWWA-amide, furthermore adopt a moderate average tilt within lipid bilayer membranes. To understand the anchor residue dependence of the tilt, we introduce Leu-Ala "spacers" between paired anchors and in some cases replace the outer tryptophans. The resulting peptides, acetyl-GX 2 ALW(LA) 6 LWLAX 22 A-amide, have Trp, Lys, Arg, or Gly in the two X positions. The apparent average orientations of the core helical sequences were determined in oriented phosphatidylcholine bilayer membranes of varying thickness using solid-state 2 H NMR spectroscopy. When X is Lys, Arg, or Gly, the direction of the tilt is essentially constant in different lipids and presumably is dictated by the tryptophans (Trp 5 and Trp 19 ) that flank the inner helical core. The Leu-Ala spacers are no longer helical. The magnitude of the apparent helix tilt furthermore scales nicely with the bilayer thickness except when X is Trp. When X is Trp, the direction of tilt is less well defined in each phosphatidylcholine bilayer and varies up to 70°among 1,2-dioleoyl-sn-glycero-3-phosphocholine, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, and 1,2-dilauroylsn-glycero-3-phosphocholine bilayer membranes. Indeed, the X ‫؍‬ Trp case parallels earlier observations in which WALP family peptides having multiple Trp anchors show little dependence of the apparent tilt magnitude on bilayer thickness. The results shed new light on the interactions of arginine, lysine, tryptophan, and even glycine at lipid bilayer membrane interfaces.The lipid bilayer environment has a profound influence on the properties of peptides and proteins found within it. It is significant that many membrane-spanning proteins have bands of aromatic and/or positively charged residues at the membrane interface, which could serve as anchors for the protein orientation and promote favorable protein-lipid interactions. This anchoring is a widespread characteristic that is observed for a variety of proteins having both ␣ and ␤ transmembrane folds (1-5). Furthermore, polar amino acids influence the topology of membrane proteins as the direction of insertion is driven by the asymmetric positioning of basic residues (Lys and Arg), giving rise to the "positive inside" rule for helical membrane proteins (6). Little is known, nevertheless, about the contributions of these residues in defining the orientations of the transmembrane segments within lipid bilayers (7).Due to the inherent complexity of membrane proteins in the native biological membrane environment, model systems provide meaningful ways to address specific questions about protein/lipid interactions. In particular, model peptides of the WALP family, having the general sequence acetyl-GWW-(LA) n LWWA- [ethanol]amide, have yielded valuable information about peptide orientations, dynam...

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Section: Methodsmentioning

confidence: 99%

Charged or Aromatic Anchor Residue Dependence of Transmembrane Peptide Tilt

Vostrikov

Daily

Greathouse

et al. 2010

Journal of Biological Chemistry

185

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“…9,10 The introduction of the alkoxycarbonyl moiety was first carried out under weakly basic conditions via the Schotten-Baumann reaction, by using the corresponding chloroformates (also known as chlorides). 3 However, our group 11 and others [12][13][14][15] described in the early eighties that during the preparation of Fmocamino acids from Fmoc-Cl, most amino acids become contaminated with significant levels (1-20%) of corresponding Fmoc-dipeptides and even tripeptides. As an example, even when the relatively hindered Alloc-Val-OH was prepared in a laboratory scale, 14% of the corresponding dipeptide was obtained.…”

mentioning

confidence: 96%

Fmoc‐2‐mercaptobenzothiazole, for the introduction of the Fmoc moiety free of side‐reactions

et al. 2007

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A double side-reaction, consisting in the formation of Fmoc-beta-Ala-OH and Fmoc-beta-Ala-AA-OH, during the preparation of Fmoc protected amino acids (Fmoc-AA-OH) with Fmoc-OSu is discussed. Furthermore, the new Fmoc-2-MBT reagent is proposed for avoiding these side-reactions as well as the formation of the Fmoc-dipeptides (Fmoc-AA-AA-OH) and even tripeptides, which is another important side-reaction when chloroformates such as Fmoc-Cl is used for the protection of the alpha-amino function of the amino acids.

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“…[11] Nevertheless, it has been reported that the high reactivity of these chlorides, such as Fmoc-Cl (1) or Alloc-Cl (2), might lead to the formation of amino-acid-based byproducts, including the protection of bulky residues, that become inserted into the peptide chain. [12][13][14][15][16] As result of this detrimental side reaction, considerable formation of Fmoc/Alloc-dipeptides and tripeptides (1-20 %) has been observed, as established by HPLC, amino acid analysis, NMR spectroscopy, and the synthesis of a number of standards. [13] A previous "in situ" bis-trimethylsilylation step of protection of the residue, before conducting the reaction with the chloroformate, can prevent the formation of such byproducts.…”

Section: Introductionmentioning

confidence: 98%

“…[13][14][15][16]26,27] Nonetheless, the formation of up to 0.4 % of some amino-acid-based byproducts like Fmoc/Alloc-β-Ala-OH and Fmoc/Alloc-β-Ala-AA-OH can occur when using this reagent for α-amino protection. [28] A detailed discussion of the mechanism of this side reaction has been proposed by Isidro-Llobet et al [25] Azide derivatives, which can be used as solids after isolation from the chloroformates [12,29] or formed in situ before reacting with the amino acid, [30] have also been proposed as an alternative pathway to the N-protection of amino acids, although its explosive nature compromises its use in large-scale synthesis.…”

Section: Introductionmentioning

confidence: 99%

Oxime Carbonates: Novel Reagents for the Introduction of Fmoc and Alloc Protecting Groups, Free of Side Reactions

Khattab¹,

Subirós‐Funosas²,

El‐Faham³

et al. 2010

Eur J Org Chem

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Fmoc and Alloc protecting groups represent a consistent alternative to classical Boc protection in peptide chemistry. The former was established in the last decades as the α‐amino protecting group of choice, whereas the latter allows a fully orthogonal protection strategy with Fmoc and Boc. Usually, the introduction of the Fmoc and Alloc moieties takes place through their halogenoformates, azides, or activated carbonates. This rather simple reaction is accompanied by several side reactions, specially the formation of Fmoc/Alloc dipeptides and even tripeptides. The present work describes new promising Fmoc/Alloc‐oxime reagents, which are easy to prepare, stable, and highly reactive crystalline materials that afford almost contaminant‐free Fmoc/Alloc‐amino acids in high yields by following a conventional procedure. Amongst the Fmoc‐oxime derivatives, the N‐hydroxypicolinimidoyl cyanide derivative (N‐{[(9H‐fluoren‐9‐yl)methoxy]carbonyloxy}picolinimidoyl cyanide) gave the best results for the preparation of Fmoc‐Gly‐OH, which is the most predisposed to give side reactions. The same Alloc‐oxime analogue afforded the preparation of Alloc‐Gly‐OH in good yield, purity, and extremely low dipeptide formation, as analyzed by reverse‐phase HPLC and NMR spectroscopy.

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Rapid and efficient method for the preparation of Fmoc‐amino acids starting from 9‐fluorenylmethanol

Abstract: A method is presented for the high‐yield synthesis of Fmoc amino acids, which precludes racemization and over‐reaction due to carboxyl activation. A detailed procedure is given for the preparation of Fmoc‐ONSu.

Cited by 105 publications

References 8 publications

Charged or Aromatic Anchor Residue Dependence of Transmembrane Peptide Tilt

Charged or Aromatic Anchor Residue Dependence of Transmembrane Peptide Tilt

Fmoc‐2‐mercaptobenzothiazole, for the introduction of the Fmoc moiety free of side‐reactions

Oxime Carbonates: Novel Reagents for the Introduction of Fmoc and Alloc Protecting Groups, Free of Side Reactions

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