COMU: A Safer and More Effective Replacement for Benzotriazole‐Based Uronium Coupling Reagents

El‐Faham, Ayman; Funosas, Ramon SubirÃ3s; Prohens, Rafel; Alberício, Fernando

doi:10.1002/chem.200900615

Cited by 276 publications

(306 citation statements)

References 98 publications

Supporting

Mentioning

296

Contrasting

Unclassified

Order By: Relevance

“…Prenylated and cysteine O-methylated peptides, labeled at their N terminus with a fluorescent S-bimanylthioacetyl residue, were synthesized using solution-phase methods as described previously (10,11,48,49). Briefly, Fmoc-FFC(trityl)-OMe, Fmoc-GGC (trityl)-OMe, and Fmoc-AAC(trityl)-OMe were first synthesized (via the appropriate dipeptide derivatives) from the appropriate Fmoc amino acids and S-tritylcysteine O-methyl ester, using (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylaminomorpholinocarbenium hexafluorophosphate (COMU) as coupling reagent (50), and then S-deprotected with trifluoroacetic acid/triethylsilane (96/4 vol/vol, 1 h, 25°C) and S-prenylated using farnesyl or geranylgeranyl bromide (10). The resulting prenylated tripeptides were extended to pentapeptides by further cycles of Fmoc deprotection and COMU-mediated coupling, using γ-2-phenylisopropyl and 4-methyltrityl protection for the side chains of glutamic acid and lysine residues, and then Fmoc deprotected and labeled on their N termini with the succinimidyl ester of S-bimanylthioacetic acid (10).…”

Section: Methodsmentioning

confidence: 99%

G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes

O’Neill¹,

Karunarathne²,

Kalyanaraman³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Activation of G-protein heterotrimers by receptors at the plasma membrane stimulates βγ-complex dissociation from the α-subunit and translocation to internal membranes. This intermembrane movement of lipid-modified proteins is a fundamental but poorly understood feature of cell signaling. The differential translocation of G-protein βγ-subunit types provides a valuable experimental model to examine the movement of signaling proteins between membranes in a living cell. We used live cell imaging, mathematical modeling, and in vitro measurements of lipidated fluorescent peptide dissociation from vesicles to determine the mechanistic basis of the intermembrane movement and identify the interactions responsible for differential translocation kinetics in this family of evolutionarily conserved proteins. We found that the reversible translocation is mediated by the limited affinity of the βγ-subunits for membranes. The differential kinetics of the βγ-subunit types are determined by variations among a set of basic and hydrophobic residues in the γ-subunit types. Gprotein signaling thus leverages the wide variation in membrane dissociation rates among different γ-subunit types to differentially control βγ-translocation kinetics in response to receptor activation. The conservation of primary structures of γ-subunits across mammalian species suggests that there can be evolutionary selection for primary structures that confer specific membrane-binding affinities and consequent rates of intermembrane movement.protein-membrane interaction | spatio-temporal dynamics | G protein-coupled receptors C ompared with the vast biochemical information available for signaling proteins from cell-disruptive techniques, much less is known about their spatiotemporal dynamics in the 3D space of an intact living cell. Many important signaling proteins are posttranslationally modified with lipid groups that facilitate their interactions with membranes. Live cell imaging has so far revealed important roles for constitutive cycles that maintain proper localization of lipidated proteins (1) and for dynamic protein redistribution throughout the cell in response to a signal (2), but the detailed nature of lipid-modified protein movement between membranes is generally not well understood.Heterotrimeric G proteins consist of lipid-modified α-and βγ-subunits (3). They are central transducers of the most important signaling pathways in mammals, yet little is known about their intracellular movement. Inactive heterotrimers consist of a GDP-bound α-subunit in complex with a stable βγ-dimer and localize to the plasma membrane (3). Extracellular signals activate transmembrane G-protein-coupled receptors (GPCRs) that catalyze nucleotide exchange on the G-protein α-subunit (3). The βγ-complex can then dissociate from the active α-subunit and translocate from the plasma membrane to intracellular membranes (4-6). βγ translocation has been observed for many different cell types and receptor types, suggesting that it is a common feature of G-protein signaling (4-...

show abstract

Section: Methodsmentioning

confidence: 99%

G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes

O’Neill¹,

Karunarathne²,

Kalyanaraman³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Accordingly, El-Faham and Albericio [25][26] reported the new additives as well as their uronium salts derivatives as replacement for HOBt and HOAt derivatives (Figures 3 and 4). Among these entire additives Oxyma [26] (Figure 3) and its uronium salt COMU (Figure 4) showed an excellent replacement for HOBt and its analogues [26,27]. synthesis [27].…”

mentioning

confidence: 99%

“…Among these entire additives Oxyma [26] (Figure 3) and its uronium salt COMU (Figure 4) showed an excellent replacement for HOBt and its analogues [26,27]. synthesis [27]. Oxyma-B, has the same structure future for the carbonyl moiety in which the oxime group is flanked between the two carbonyl group as in HONM.…”

mentioning

confidence: 99%

Peptide Coupling Reactions

Ns¹,

El‐Faham²,

Alberício³

2015

J Mol Pharm Org Process Res

View full text Add to dashboard Cite

“…Oxyma can be handled with considerably lower risk than the explosive benzotriazole, as determined by calorimetric techniques. 36,37) In the hope of suppressing the loss of chiral integrity during stepwise coupling and enhancing the coupling yield, 1-hydroxypyridin-2(1H)-one 3 and ethyl 2-cyano-2-(hydroxyimino)acetate 4 (oxyma) are used to replace HOBt 1 and HOAt 2. The reactivity of the sulphonate esters is expected to be directly related to the stability of the leaving group anions (OBt Ϫ , OAt Ϫ , PyO Ϫ and CNOEtO Ϫ ), and accordingly related to their pK a values.…”

mentioning

confidence: 99%

“…Oxyma displayed a remarkable capacity to inhibit racemization, together with impressive coupling efficiency, in both automated and manual synthesis, superior to those of HOBt and at least comparable to those of HOAt. [36][37][38] Stability assays showed that there was no risk of capping the resin under standard coupling conditions. Oxyma can be handled with considerably lower risk than the explosive benzotriazole, as determined by calorimetric techniques.…”

mentioning

confidence: 99%

Sulfonate Esters of 1-Hydroxypyridin-2(1H)-one and Ethyl 2-Cyano-2-(hydroxyimino)acetate (Oxyma) as Effective Peptide Coupling Reagents to Replace 1-Hydroxybenzotriazole and 1-Hydroxy-7-azabenzotriazole

Khattab

2010

Chem. Pharm. Bull.

View full text Add to dashboard Cite

The activation of carboxylic acids for the formation of amides or esters is an important process usually carried out using the so-called peptide coupling reagents. 1-3) This is followed by the reaction with the amine moiety of another amino acid to produce the desired peptide. The effective formation of a peptide bond not only depends on the reaction rate and yield but also on the suppression of the undesired racemization and other side reactions and thus minimizes the loss of the optical integrity at the chiral center of the carboxylic component. Preventing the loss of configuration is one of the major challenges in peptide synthesis. [4][5][6][7][8] The activation of carboxylic acids using phosphonium 9-13) and uranium salts [14][15][16][17] is a fast, reliable process. These salts are prepared from a phosphonium or uronium cation bonded generally to a XO-group, normally a hydroxylamine derivative. These salts combine the functions of activating agents with suppressing additives and were successfully introduced in peptide synthesis. 18) A common method of minimizing the loss of configuration during stepwise coupling in solution phase is to add an additive such as 1-hydroxy-benzotriazole (HOBt) to the coupling mixture. 19) Recently, 1-hydroxy-7-azabenzotriazole (HOAt) and its derived phophonium or uronium/guanidinuim salts have been described as favorable coupling additives or reagents for both solution 20) and solidphase synthesis. 21) HOAt has been reported to be more efficient than HOBt because of an anchimeric assistance effect caused by the pyridine ring. 22,23) These compounds enhance coupling yields and reduce the loss of chiral integrity during stepwise coupling.Esters of sulfonic acids and HOBt have been used for peptide coupling. [24][25][26][27][28] The reactivity of these sulfonate esters was shown to be directly related to the presence of electronwithdrawing substituents in both the HOBt and the sulfonic acid moieties. [29][30][31][32][33][34] This methodology has few applications, as the coupling process depends on the basicity and reactivity of the amino component. The use of such sulfonate esters for in situ coupling was often accompanied by the formation of a sulfonamide byproduct. 24,30) Such byproduct formation can be avoided by preactivation of the reactive carboxylic acid component.On the other hand, the use of a preactivation step is counterproductive, since the loss of configuration at the C-terminal carboxylic acid residue directly increases with preactivation time. 35) The replacement of HOBt by HOAt was expected to reduce the extent of configurational loss, but, on the contrary, the advantages of HOAt were lost during long preactivation times. 33,34) Oxyma (ethyl 2-cyano-2-(hydroxyimino)acetate) 4 has been tested as an additive for use in the carbodiimide approach for the formation of peptide bonds. It showed better performance than the classical HOBt and HOAt, which have recently been reported to exhibit explosive properties. Oxyma displayed a remarkable capacity to inhibit racemizati...

show abstract

COMU: A Safer and More Effective Replacement for Benzotriazole‐Based Uronium Coupling Reagents

Cited by 276 publications

References 98 publications

G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes

G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes

Peptide Coupling Reactions

Sulfonate Esters of 1-Hydroxypyridin-2(1H)-one and Ethyl 2-Cyano-2-(hydroxyimino)acetate (Oxyma) as Effective Peptide Coupling Reagents to Replace 1-Hydroxybenzotriazole and 1-Hydroxy-7-azabenzotriazole

Contact Info

Product

Resources

About