Photoremovable protecting groups based on photoenolization

Sankaranarayanan, Jagadis; Muthukrishnan, Siva; Guđmundsdóttir, Anna D.

doi:10.1016/s0065-3160(08)00002-6

Cited by 24 publications

(27 citation statements)

References 163 publications

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“…Another method of conformational switching is to use a relatively large molecular moiety (i.e., a cage) to force the protein of interest to unfold under native conditions; on cleavage of the cage by excitation with an appropriate laser pulse, the protein will fold to its native conformation. Thus, several photocages, such as benzoinyl cages, have been used to trigger protein folding kinetics 39–43. Photocaged molecules can also be used in a cyclization scheme to produce a photocleavable intramolecular linker.…”

Section: Triggering Methodsmentioning

confidence: 99%

Spectroscopic studies of protein folding: Linear and nonlinear methods

2011

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Although protein folding is a simple outcome of the underlying thermodynamics, arriving at a quantitative and predictive understanding of how proteins fold nevertheless poses huge challenges. Therefore, both advanced experimental and computational methods are continuously being developed and refined to probe and reveal the atomistic details of protein folding dynamics and mechanisms. Herein, we provide a concise review of recent developments in spectroscopic studies of protein folding, with a focus on new triggering and probing methods. In particular, we describe several laser-based techniques for triggering protein folding/unfolding on the picosecond and/or nanosecond timescales and various linear and nonlinear spectroscopic techniques for interrogating protein conformations, conformational transitions, and dynamics.

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Section: Triggering Methodsmentioning

confidence: 99%

Spectroscopic studies of protein folding: Linear and nonlinear methods

2011

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“…Photoenolization is a light-initiated keto-enol tautomerization process, and the resulting photoenols are high-energy ground state intermediates that are highly reactive (1,2). Efficient photoenol reactivity has been captured in applications such as synthesizing complex natural products and pharmaceutical drugs, and initiating release from photoremovable protecting groups (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). The mechanism of photoenolization, which has been determined using transient spectroscopy, can be outlined as follows: Upon excitation ortho-substituted aryl ketones form the singlet excited state of the ketone chromophore, which undergoes efficient intersystem crossing to form its triplet configuration (Scheme 1) (15)(16)(17)(18)(19).…”

Section: Introductionmentioning

confidence: 99%

Steric Demand and Rate‐determining Step for Photoenolization of Di‐ortho‐substituted Acetophenone Derivatives

Das

Thomas

Garofoli

et al. 2018

Photochem & Photobiology

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Laser flash photolysis of ketone 1 in argon-saturated methanol yields triplet biradical 1BR (τ = 63 ns) that intersystem crosses to form photoenols Z-1P (λ = 350 nm, τ ~ 10 μs) and E-1P (λ = 350 nm, τ > 6 ms). The activation barrier for Z-1P re-forming ketone 1 through a 1,5-H shift was determined as 7.7 ± 0.3 kcal mol . In contrast, for ketone 2, which has a less sterically hindered carbonyl moiety, laser flash photolysis in argon-saturated methanol revealed the formation of biradical 2BR (λ = 330 nm, τ ~ 303 ns) that intersystem crosses to form photoenol E-2P (λ = 350 nm, τ > 42 μs), but photoenol Z-2P was not detected. However, in more viscous basic H-bond acceptor (BHA) solvent, such as hexamethylphosphoramide, triplet 2BR intersystem crosses to form both Z-2P (λ = 370 nm, τ ~ 1.5 μs) and E-2P. Thus, laser flash photolysis of ketone 2 in methanol reveals that intersystem crossing from 2BR to form Z-2P is slower than the 1,5-H shift of Z-2P, whereas in viscous BHA solvents, the 1,5-H shift becomes slower than the intersystem crossing from 2BR to Z-2P. Density functional theory and coupled cluster calculations were performed to support the reaction mechanisms for photoenolization of ketones 1 and 2.

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“…13 The ability to selectively trigger reactions by irradiation, independently of pH, temperature or other reaction conditions, resulted in the use of photochemical reactions as key steps in natural product synthesis 14,15 and also in the development of photolabile protecting groups for multistep organic chemistry. [16][17][18][19][20][21][22][23][24] The high wavelength selectivity of different photoreactions even allowed individual removal of different photolabile protecting groups by irradiation at different wavelengths. 25,26 Because light can be easily controlled spatially and temporally, photochemical reactions were used to regulate or explore biological processes by the use of so-called caged compounds in which a desired biological activity can be triggered reversibly ( photoisomerisation) or irreversibly ( photocleavage) by irradiation.…”

Section: Introductionmentioning

confidence: 99%

Using photolabile protecting groups for the controlled release of bioactive volatiles

Herrmann

2012

Photochem Photobiol Sci

102

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To develop their biological activity, bioactive volatile compounds, such as pheromones or fragrances, have to evaporate from surfaces. Because these surfaces are usually exposed to natural daylight, the preparation of non-volatile precursors using photoremovable protecting groups is an ideal tool to control the release of caged volatile molecules from various surfaces by light-induced covalent bond cleavage. Many photoreactions occur under mild environmental conditions and are highly selective. To break covalent bonds under typical application conditions, the photoreaction has to proceed at ambient daylight, to tolerate the presence of oxygen and to run in polar media (e.g. in water). The amount of volatiles generated from photochemical delivery systems depends on the light intensity to which the systems are exposed. Both photoisomerisations and photofragmentations have successfully been investigated for the slow release of caged pheromones and fragrances from their corresponding precursors.

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Photoremovable protecting groups based on photoenolization

Cited by 24 publications

References 163 publications

Spectroscopic studies of protein folding: Linear and nonlinear methods

Spectroscopic studies of protein folding: Linear and nonlinear methods

Steric Demand and Rate‐determining Step for Photoenolization of Di‐ortho‐substituted Acetophenone Derivatives

Using photolabile protecting groups for the controlled release of bioactive volatiles

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