Comparison of boron-assisted oxime and hydrazone formations leads to the discovery of a fluorogenic variant

Stress, Cedric; Schmidt, Pascal J.; Gillingham, Dennis

doi:10.1039/c6ob00168h

Cited by 51 publications

(68 citation statements)

References 28 publications

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“…Recently, we 14–16 and others 17–21 have demonstrated the thermodynamic and kinetic benefit of an ortho -boronic acid moiety in the formation of imines, as well as oximes and hydrazones. As thiazolidine formation potentially goes through an imine intermediate, we hypothesized that a boronic acid moiety installed at the ortho position of benzaldehyde would be able to activate the imine to facilitate thiazolidine formation (Figure 1b).…”

Section: Resultsmentioning

confidence: 98%

Fast and selective labeling of N-terminal cysteines at neutral pH via thiazolidino boronate formation

2016

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Section: Resultsmentioning

confidence: 98%

Fast and selective labeling of N-terminal cysteines at neutral pH via thiazolidino boronate formation

2016

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“…126 Most notably, those BIQs proved to form irreversibly and thus they were found to be indefinitely stable in aqueous solution. This approach could be further developed into a fluorogenic reaction by using 2-hydrazinylphenol as a substrate, which results in the formation of highly emissive tetracyclic BIQ 108 .…”

Section: Stability Factorsmentioning

confidence: 99%

“…126 In this design, reactants are again rapidly trapped at the tetrahedral intermediate stage 162 / 163 , with the oxyanion coordinated to boron, and then more slowly rearrange to oximes 164 (Scheme 19). This strategy is an important new reaction for bioconjugation development.…”

Section: Discovery and Design Of Fast-reacting Substratesmentioning

confidence: 99%

Oximes and Hydrazones in Bioconjugation: Mechanism and Catalysis

2017

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The formation of oximes and hydrazones is employed in numerous scientific fields as a simple and versatile conjugation strategy. This imine-forming reaction is applied in fields as diverse as polymer chemistry, biomaterials and hydrogels, dynamic combinatorial chemistry, organic synthesis, and chemical biology. Here we outline chemical developments in this field, with special focus on the past ∼10 years of developments. Recent strategies for installing reactive carbonyl groups and α-nucleophiles into biomolecules are described. The basic chemical properties of reactants and products in this reaction are then reviewed, with an eye to understanding the reaction's mechanism and how reactant structure controls rates and equilibria in the process. Recent work that has uncovered structural features and new mechanisms for speeding the reaction, sometimes by orders of magnitude, is discussed. We describe recent studies that have identified especially fast reacting aldehyde/ketone substrates and structural effects that lead to rapid-reacting α-nucleophiles as well. Among the most effective new strategies has been the development of substituents near the reactive aldehyde group that either transfer protons at the transition state or trap the initially formed tetrahedral intermediates. In addition, the recent development of efficient nucleophilic catalysts for the reaction is outlined, improving greatly upon aniline, the classical catalyst for imine formation. A number of uses of such second- and third-generation catalysts in bioconjugation and in cellular applications are highlighted. While formation of hydrazone and oxime has been traditionally regarded as being limited by slow rates, developments in the past 5 years have resulted in completely overturning this limitation; indeed, the reaction is now one of the fastest and most versatile reactions available for conjugations of biomolecules and biomaterials.

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“…11 Interestingly, the diazaborine product was found to survive boiling in solutions of either 10% HCl or 10% KOH. Recent and more detailed studies by the Bane 12 and Gillingham 13 groups revealed that the 2-FPBA-phenylhydrazine conjugation proceeds with rate constants over 10 3 M −1 s -1 . Despite the fast kinetics, this conjugation reaction remains less ideal for biological applications due to the poor stability and cytotoxicity of phenylhydrazine ( vide infra ), in addition to the high reactivity of 2-FPBA toward endogenous cysteines.…”

Section: Introductionmentioning

confidence: 99%

Fast Diazaborine Formation of Semicarbazide Enables Facile Labeling of Bacterial Pathogens

2017

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Bioorthogonal conjugation chemistry has enabled the development of tools for the interrogation of complex biological systems. Although a number of bioorthogonal reactions have been documented in literature, they are less ideal for one or several reasons including slow kinetics, low stability of the conjugated product, requirement of toxic catalysts, and side reactions with unintended biomolecules. Herein we report a fast (>103 M−1s−1) and bioorthogonal conjugation reaction that joins semicarbazide to an aryl ketone or aldehyde with an ortho-boronic acid substituent. The boronic acid moiety greatly accelerates the initial formation of a semicarbazone conjugate, which rearranges into a stable diazaborine. The diazaborine formation can be performed in blood serum or cell lysates with minimal interference from biomolecules. We further demonstrate that application of this conjugation chemistry enables facile labeling of bacteria. A synthetic amino acid D-AB3, which presents a 2-acetylphenylboronic acid moiety as its side chain, was found to incorporate into several bacterial species through cell wall remodeling, with particularly high efficiency for Escherichia coli. Subsequent D-AB3 conjugation to a fluorophore-labeled semicarbazide allows robust detection of this bacterial pathogen in blood serum.

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Comparison of boron-assisted oxime and hydrazone formations leads to the discovery of a fluorogenic variant

Cited by 51 publications

References 28 publications

Fast and selective labeling of N-terminal cysteines at neutral pH via thiazolidino boronate formation

Fast and selective labeling of N-terminal cysteines at neutral pH via thiazolidino boronate formation

Oximes and Hydrazones in Bioconjugation: Mechanism and Catalysis

Fast Diazaborine Formation of Semicarbazide Enables Facile Labeling of Bacterial Pathogens

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