Diffusion-controlled proton transfer in intramolecular thiol ester aminolysis and thiazoline hydrolysis

Barnett, Ronald E.; Jencks, William P.

doi:10.1021/ja01037a029

Cited by 57 publications

(34 citation statements)

References 5 publications

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“…Thus, on the basis of these precedents and the inverse beta-secondary isotope effect observed in our studies here, formation of a tetrahedral intermediate during cyclization of glutamine can be invoked. Also, previous studies on the aminolysis of acetate and thiol esters provided evidence for a rate-determining proton transfer [19,1,4].…”

Section: Discussionmentioning

confidence: 87%

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Phosphate ions and glutaminyl cyclases catalyze the cyclization of glutaminyl residues by facilitating synchronized proton transfers

Seifert

Demuth

Weichler

et al. 2015

Bioorganic Chemistry

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Section: Discussionmentioning

confidence: 87%

“…The principal mechanism of such reactions has been studied in detail [19,1,17]. For related model reactions, it is assumed that a tetrahedral intermediate is transiently formed, and that breakdown of this tetrahedral intermediate is rate limiting for the overall reaction [17].…”

Section: Discussionmentioning

confidence: 99%

Phosphate ions and glutaminyl cyclases catalyze the cyclization of glutaminyl residues by facilitating synchronized proton transfers

Seifert

Demuth

Weichler

et al. 2015

Bioorganic Chemistry

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“…27 The acylotropic prototropic isomerization of com pound 6e is evidently asynchronous. The initial step in volves the migration exclusively of the acetyl group, where as the migration of the proton of the NH group begins only after the reaction system reaches the transition state TS4.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of N-unsubstituted 2-arylpyrazolo[1,5-a]benzimidazoles from 1-benzylideneamino-2-methylbenzimidazole and the role of acylotropic and acylotropic-prototropic isomerization

2011

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2 Aryl 4H pyrazolo[1,5 a]benzimidazoles were synthesized for the first time from 1 benzyl ideneamino 2 methylbenzimidazole by the benzoylation of the methyl group followed by the cyclization of the resulting vinyl acylates in concentrated HCl. The key steps of the process were studied by quantum chemical methods for model systems. It was shown that the concerted intramolecular acylotropic and acylotropic prototropic transformations play an important role in this process.Key words: 1 benzylideneamino 2 methylbenzimidazole, 4H pyrazolo[1,5 a]benzimid azole, quantum chemical calculations, density functional theory, B3LYP density functional, transition states, acylotropic and acylotropic prototropic isomerization.

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“…The thioester group has a strong UV absorption at 230 nm with an extinction coefficient ( ε ) of 4300 M −1 cm −1 compared to that of the amide group ( ε = 122 M −1 cm −1 ) [16]. Thus, the change in the S -palmitoyl content, or concentration ( c ), under various incubation conditions can be studied by monitoring the UV absorbance ( A ) at 230 nm, according to the Lambert-Beer Law: A = εcL , where L is the light path length.…”

Section: Resultsmentioning

confidence: 99%

S- to N-Palmitoyl Transfer During Proteomic Sample Preparation

Bachschmid

Costello

et al. 2016

J. Am. Soc. Mass Spectrom.

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N-palmitoylation has been reported in a number of proteins and suggested to play an important role in protein localization and functions. However, it remains unclear whether N-palmitoylation is a direct enzyme-catalyzed process, or results from intramolecular S- to N-palmitoyl transfer. Here, using the S-palmitoyl peptide standard, GCpalmLGNAK, as the model system, we observed palmitoyl migration from the cysteine residue to either the peptide N-terminus or the lysine side chain during incubation in both neutral and slightly basic buffers commonly used in proteomic sample preparation. Palmitoyl transfer can take place either intra- or inter-molecularly, with the peptide N-terminus being the preferred migration site, presumably due to its lower basicity. The extent of intramolecular palmitoyl migration was low in the system studied, as it required the formation of an entropically unfavored macrocycle intermediate. Intermolecular palmitoyl transfer, however, remained a tangible problem, and may lead to erroneous reporting of in vivo N-palmitoylation. It was found that addition of the MS-compatible detergent RapiGest could significantly inhibit intermolecular palmitoyl transfer, as well as thioester hydrolysis and DTT-induced thioester cleavage. Finally, palmitoyl transfer from the cysteine residue to the peptide N-terminus can also occur in the gas phase, during collision-induced dissociation, and result in false identification of N-palmitoylation. Therefore, one must be careful with both sample preparation and interpretation of tandem mass spectra in the study of N-palmitoylation.

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Diffusion-controlled proton transfer in intramolecular thiol ester aminolysis and thiazoline hydrolysis

Cited by 57 publications

References 5 publications

Phosphate ions and glutaminyl cyclases catalyze the cyclization of glutaminyl residues by facilitating synchronized proton transfers

Phosphate ions and glutaminyl cyclases catalyze the cyclization of glutaminyl residues by facilitating synchronized proton transfers

Synthesis of N-unsubstituted 2-arylpyrazolo[1,5-a]benzimidazoles from 1-benzylideneamino-2-methylbenzimidazole and the role of acylotropic and acylotropic-prototropic isomerization

S- to N-Palmitoyl Transfer During Proteomic Sample Preparation

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