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1.
Perylen-3-ylmethyl demonstrated as a new fluorescent photoremovable protecting group (FPRPG) for carboxylic acids and alcohols. Carboxylic acids including amino acids were protected as their corresponding esters by coupling with FPRPG, perylen-3-ylmethyl. Photophysical studies of caged esters showed that they all exhibited strong fluorescence properties and their fluorescence quantum yields were in the range of 0.85–0.95. Irradiation of the caged esters using visible light (≥410 nm) in aqueous acetonitrile released the corresponding carboxylic acids in high chemical (94–97%) and quantum (0.072–0.093) yields. The results obtained from the photolysis of the caged ester in different solvents indicated that solvent has influence on the rate of photorelease. Further, we also explored the ability of FPRPG, perylen-3-ylmethyl for the protection of alcohols and phenols. 相似文献
2.
Lin Q Bao C Cheng S Yang Y Ji W Zhu L 《Journal of the American Chemical Society》2012,134(11):5052-5055
A new concept in which only the molecular target, such as a thiol-bearing protein, can activate the phototrigger has been demonstrated. Such target-activatable phototriggers comprise three parts: a 7-aminocoumarin phototrigger, an electron acceptor (maleimide) that efficiently quenches the coumarin excited state, and a caged leaving group attached to the coumarin. In the absence of mercaptans, photoinduced electron transfer between coumarin and maleimide effectively blocks both the fluorescence and photocleavage pathways. Thiol-bearing molecules, however, readily annihilate the electron acceptor and thus restore the phototrigger for photorelease of the caged cargo (e.g., biotin). Unlike traditional phototriggers, functional-group-activated phototriggers allow easy handling under ambient light, report specific bonding to the target, and enable photocleavage capability selectively at the binding site in situ, thus effectively positioning the photoreleased cargo at the target. Meanwhile, the unique feature of thiol-specific activation of the fluorescence and photocleavage make our new phototrigger a universal tool that can be used to identify accurately protein cysteine S-nitrosylation, a physiologically important posttranslational modification. 相似文献
3.
A series of anticancer prodrugs with different chemical functional groups were prepared, in which the styryl conjugated 2-nitrobenzyl derivatives were introduced as the phototrigger to regulate the drug (chlorambucil) release. Compared to the common 4,5-dimethoxy-2-nitrobenzyl caged compounds, most of the prodrugs exhibited large and redshifted one-photon absorption within the visible range. One-photon excitation for the drug release was studied by measuring UV-vis absorption, FT-IR, and HPLC spectra, which suggested that chlorambucil was released effectively and precisely by manipulating external light conditions. And the introduction of different functional groups made this type of prodrug a good platform to further react with some typical drug carriers and to further form excellent visible light responsive drug delivery systems. Moreover, the drug also could be effectively released under the excitation of two-photon at 800 nm with comparable photorelease efficiencies. 相似文献
4.
Photorelease of caged Ca(2+) is a uniquely powerful tool to study the dynamics of Ca(2+)-triggered exocytosis from individual cells. Using photolithography and other microfabrication techniques, we have developed transparent microchip devices to enable photorelease of caged Ca(2+), together with electrochemical detection of quantal catecholamine secretion from individual cells or cell arrays as a step towards developing high-throughput experimental devices. A 100 nm thick transparent indium-tin-oxide (ITO) film was sputter-deposited onto glass coverslips, which were then patterned into 24 cell-sized working electrodes (approximately 20 microm by 20 microm). We loaded bovine chromaffin cells with acetoxymethyl (AM) ester derivatives of the Ca(2+) cage NP-EGTA and Ca(2+) indicator dye fura-4F, then transferred these cells onto the working ITO electrodes for amperometric recordings. Upon flash photorelease of caged Ca(2+), a uniform rise of [Ca(2+)](i) within the target cell leads to quantal release of oxidizable catecholamines measured amperometrically by the underlying ITO electrode. We observed a burst of amperometric spikes upon rapid elevation of [Ca(2+)](i) and a "priming" effect of sub-stimulatory [Ca(2+)](i) on the response of cells to subsequent [Ca(2+)](i) elevation, similar to previous reports using different techniques. We conclude that UV photolysis of caged Ca(2+) is a suitable stimulation technique for higher-throughput studies of Ca(2+)-dependent exocytosis on transparent electrochemical microelectrode arrays. 相似文献
5.
Photolabile coumarinylmethyl esters of biomolecules (caged compounds) are new tools for studying spatial and time-dependent aspects of signal transduction in living cells. Herein we describe a fluoresence spectroscopic method for the determination of the rate constants of the photolysis steps of such caged compounds using (6.7-dimethoxycoumarin-4-yl)methyl diethyl phosphate (DMCM-DEP) and sodium (6,7-dimethoxycoumarin-4-yl)methyl sulfate (DMCM-S). DMCM-DEP and DMCM-S are caged compounds which photorelease a proton, the corresponding acid anion, and the strongly fluorescent alcohol DMCM-OH upon excitation. The results of stationary and time-resolved measurements of the photochemistry and the luminescence of both caged compounds indicate that DMCM-OH is produced already during the excitation pulse. The quantitative analysis of the data demonstrates that the first step of the reaction--heterolytic bond cleavage of the coumarinylmethyl ester leading to the ion pair of a DMCM cation and an acid anion--is very fast with a rate constant of k1 approximately 2 x 10(10) s(-1). Recombination of the ion pair occurs with a rate constant of k(rec) approximately 2.3 x 10(9) s(-1) and is about 10 times faster than the competing hydrolysis reaction of the DMCM cation yielding DMCM-OH and a proton. Thus, both caged compounds belong to the fastest phototriggers known. 相似文献
6.
Cürten B Kullmann PH Bier ME Kandler K Schmidt BF 《Photochemistry and photobiology》2005,81(3):641-648
The photorelease of a caged neurotransmitter can be used to investigate the function of neuronal circuits in tissues. We have designed and synthesized a stable, caged gamma-aminobutyric acid (GABA) derivative, 4-[[(2H-1-benzopyran-2-one-7-amino-4-methoxy)carbonyl]amino] butanoic acid (BC204), that releases the neurotransmitter in physiological medium when irradiated with UV light at 300-400 nm in PBS at pH 7.4. The release of GABA occurs with the formation of the major photoproduct, 7-amino-4-(hydroxymethyl)-2H-1-benzopyran-2-one, via a solvolytic photodegradation mechanism of the coumarin moiety and was confirmed by electrospray mass spectrometry/mass spectrometry (ESI MS/MS). BC204 is chemically stable and shows no intrinsic activity after many hours under physiological dark conditions. These properties suggest that BC204 is an excellent form of caged GABA that is well suited for long-term biological studies. 相似文献
7.
Stanton-Humphreys MN Taylor RD McDougall C Hart ML Brown CT Emptage NJ Conway SJ 《Chemical communications (Cambridge, England)》2012,48(5):657-659
Irradiation of a mixture of 4-methoxyphenacyl-caged (S)-glutamate and 4,5-dimethoxy-2-nitrobenzyl-caged γ-amino butyric acid (GABA) on neurons, at ~260 nm, evokes selective photorelease of (S)-glutamate (Glu) whereas photolysis at 405 nm causes selective photorelease of GABA. 相似文献
8.
The photolytic release of substrates from caged substrates has proven to be an excellent method to generate concentration jumps for kinetic measurements in the microsecond time scale. In this report we use time-resolved FTIR in the step-scan mode to probe the photolysis mechanism of one such caged compound, namely gamma-(alpha-carboxy-2-nitrobenzyl)glutamate, and to obtain a direct measure of the rate of photorelease of the substrate glutamate. The time-resolved difference FTIR spectra exhibit specific signals that can be assigned to the reactant caged glutamate, photolytically released product glutamate, as well as to the aci-nitro intermediate, the key intermediate of the photolysis reaction. Therefore these signals allow the characterization of the kinetics of formation and decay of the intermediate and products. This is the first such report that provides a direct determination of the rate of formation of the photolysis product from a caged compound in the microsecond time scale. Furthermore, the results presented provide a good basis for further time-resolved FTIR studies of molecular reaction mechanisms, such as ligand protein interactions, in the microsecond time scale through the photolytic release of substrates from caged compounds. 相似文献
9.
Banerjee A Grewer C Ramakrishnan L Jäger J Gameiro A Breitinger HG Gee KR Carpenter BK Hess GP 《The Journal of organic chemistry》2003,68(22):8361-8367
The synthesis and characterization of a new photolabile protecting group (caging group) for carboxylic acids, the 2-(dimethylamino)-5-nitrophenyl (DANP) group, is described. This compound has a major absorption band in the visible wavelength region with a maximum near 400 nm (epsilon400 = 9077 M(-1) cm(-1) at pH 7.4 and 21 degrees C). The caging group is attached through an ester linkage to the carboxyl functionality of beta-alanine, which activates the inhibitory glycine receptor in the mammalian central nervous system. Such caged compounds play an important role in transient kinetic investigations of fast cellular processes. Upon photolysis of DANP-caged beta-alanine, the caging group is released within 5 micros. Quantum yields of 0.03 and 0.002 were obtained in the UV region (308 and 360 nm) and the visible region (450 nm), respectively. Laser-pulse photolysis experiments, using 337 or 360 nm light, were performed with the caged compound equilibrated with HEK 293 cells transiently transfected with cDNA encoding the alpha1 homomeric, wild-type glycine receptor. The experiments demonstrated that neither DANP-caged beta-alanine nor its byproducts inhibit or activate the glycine receptors on the cell surface. Under physiological conditions, the DANP-caged beta-alanine is water-soluble and stable and can be used for transient kinetic measurements. 相似文献
10.
The synthesis of caged NADP analogues 18, 19, and 20 has been accomplished by utilizing the transglycosidase activity of solubilized NAD glycohydrolase (porcine brain) to incorporate caged nicotinamides 2, 3, and 4 into NADP. The synthesis of several nicotinamides modified at the carboxamide with o-nitrobenzyl photolabile groups is demonstrated as well as their potential for enzymatic transglycosidation. These results further demonstrate the feasibility of direct enzymatic transglycosidation of sterically hindered substrates into NAD(P), although high nicotinamide analogue water solubility was found to be a necessary trait for yield enhancement with certain analogues. Caged analogues were surveyed under aqueous conditions for net NADP photorelease, while the UV and fluorescent properties of both analogues and their photobyproducts were assessed for compatibility with systems that rely on optical monitoring of enzyme activity. A highly water-soluble alpha-methyl-o-nitrobenzyl group 8 was developed for the synthesis of 20 in order to enhance net NADP photorelease. Compound 20 demonstrated a high 75% net NADP photoreleased without substantial UV optical blackening or fluorescent byproducts. Analogues 18 and 19 were shown by ESI/MALDI-MS to photogenerate primarily adducts of NADP with deleterious UV and fluorescent properties. Our work stresses the superior release properties conferred by alpha-methyl substitution on aqueous carboxamide photorelease from o-nitrobenzyl compounds. 相似文献
11.
Visible light (>450 nm) is used to efficiently cleave carboxylic acids, amino acids, and phosphates from their N-methyl picolinium esters. Photolysis using pyrromethene dyes PM 546 and PM 597 and also coumarin 6 as photosensitizers effects release of carboxylic acids, N-protected amino acids, and phosphates in quantitative yields. The effective rate of photorelease by the dyes, Phiepsilon, was found to be as high as 4500 M-1 cm-1. The photorelease proceeds through photoinduced electron transfer from the dye sensitizers to the N-methyl picolinium group. Fluorescence quenching and laser flash photolysis experiments support the photoinduced electron-transfer mechanism. 相似文献
12.
Optical release of spirotetramat-enol was achieved by attaching coumarin photocage. 相似文献
13.
Intracellular Thiols and Photo‐Illumination Sequentially Activate Doubly Locked Molecular Probes for Long‐Term Cell Highlighting and Tracking with Precise Spatial Accuracy
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Dr. Qiuning Lin Zengmin Du Yunlong Yang Qian Fang Prof. Chunyan Bao Prof. Yi Yang Prof. Linyong Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16314-16319
A novel photoconvertible fluorescent probe, which can be activated by intracellular thiols, has been synthesized. Such a molecular probe comprises three parts: a 7‐aminocoumarin phototrigger, a thiol‐removable energy acceptor, and a caged fluorescein scaffold with intracellular thiols reactivity as the fluorescent reporter. Extracellularly, the energy acceptor blocks the emission of the coumarin that regulates the photocleavage and photoactivation of the fluorescein. Intracelluarly, the high concentration of thiols releases the energy acceptor, thus activating the S1 state of the phototrigger, which emits coumarin blue fluorescence for pre‐visualization and liberates the caged green‐fluorescent fluorescein to highlight the specific cell upon illumination. Compared to traditional photoactivated organic dyes, the intracellular thiols activated probe requires double activations: one by intracellular thiols and the other by light activation. The dual activations restrict fluorescence precisely inside live cells and at the particular spatial region of light activation, thus a probe with precise spatial accuracy in live cells. 相似文献
14.
Yusuke Hotta Tsukasa Kaneko Ryuji Hayashi Akito Yamamoto Shota Morimoto Junya Chiba Takenori Tomohiro 《化学:亚洲杂志》2019,14(3):398-402
We developed a novel diazirine‐based photolabeling agent having a (coumarin‐4‐yl)methyl ester scaffold, which exhibited multiple photochemical properties of crosslinking, fluorogenicity and cleavage. These properties can be kinetically regulated via photoinduced electron transfer between diazirine and coumarin moieties. The C?O bond of (coumarin‐4‐yl)methyl ester can be cleaved via photochemical excitation of coumarin moiety, that function has been initially quenched by the diazirine moiety. Upon diazirine photolysis with 365‐nm light, interacting protein was stably captured with photoactivatable ligand probe. Then, the unlocked cleavage function was activated with 313 nm light, and the reaction was accelerated in a weakly‐basic solution. The crosslinked protein could be selectively isolated with attachment of a small coumarin tag on the surface. This multi‐functional labeling agent has a great potential to facilitate LC‐MS/MS‐based protein identification. 相似文献
15.
Zhao Y Zheng Q Dakin K Xu K Martinez ML Li WH 《Journal of the American Chemical Society》2004,126(14):4653-4663
Photocaged fluorescent molecules are important research tools for tracking molecular dynamics with high spatiotemporal resolution in biological systems. We have designed and synthesized a new class of caged coumarin fluorophores. These coumarin cages displayed more than 200-fold fluorescence enhancement after UV photolysis. Remarkably, the uncaging cross section of a 1-(2-nitrophenyl)ethyl (NPE)-caged coumarin is 6600 at wavelength of 365 nm, about 2 orders of magnitude higher than previously described caged fluorophores. Product analysis of the photolytic reaction showed clean conversion of NPE-caged coumarin to 2-nitrosoacetophenone and the parent coumarin, suggesting that the mechanism of the photolysis follows the known photochemical reaction pathway of the 2-nitrobenzyl group. We have also measured the two-photon uncaging cross sections of NPE-caged coumarins 2a and 5 at 740 nm to be near 1 Goeppert-Mayer (GM). The mechanistic study, together with the two-photon uncaging data, suggested that the coumarin moiety serves as an antenna to enhance the light harvesting efficiency of the coumarin cage and that the photonic energy absorbed by coumarin was utilized efficiently to photolyze the NPE group. Future explorations of this type of "substrate-assisted photolysis" may yield other cages of high uncaging cross sections. For cellular imaging applications, we prepared a cell permeable and caged coumarin fluorophore, NPE-HCCC2/AM (10), which can be loaded into fully intact cells to high concentrations. Initial tests of this probe in a number of cultured mammalian cells showed desired properties for the in vivo imaging applications. The combined advantages of robust fluorescence contrast enhancement, remarkably high uncaging cross sections, noninvasive cellular delivery, and flexible chemistry for bioconjugations should generate broad applications of these caged coumarins in biochemical and biological research. 相似文献
16.
17.
《Chemistry & biology》1997,4(11):867-878
Background: Photolabile chelators that release Ca2+ upon illumination have been used extensively to dissect the role of this important second messenger in cellular processes such as muscle contraction and synaptic transmission. The caged calcium chelators that are presently available are often limited by their inadequate changes in Ca2+ affinity, selectivity for Ca2+ over Mg2+ and sensitivity to light. As these chelators are all based on nitrobenzyl photochemistry, we explored the use of other photosensitive moieties to generate a new caged calcium with improved properties.Results: Azid-1 is a novel caged calcium in which a fluorescent Ca2+ indicator, fura-2, has been modified with an azide substituent on the benzofuran 3-position. Azid-1 binds Ca2+ with a dissociation constant (Kd) of ∼230 nM, which changes to 120 μM after photolysis with ultraviolet light (330–380 nm). Mg2+ binding is weak (8–9 mM Kd) before or after photolysis. Azid-1 photolyzes with unit quantum efficiency, making it 40–170-fold more sensitive to light than caged calciums used previously. The photolysis of azid-1 probably releases N2 to form a nitrenium ion that adds water to yield an amidoxime cation; the electron-with-drawing ability of the amidoxime cation reduces the chelator's Ca2+ affinity within at most 2 ms following a light flash. The ability of azid-1 to function as a caged calcium in living cells was demonstrated in cerebellar Purkinje cells, in which Ca2+ photolytically released from azid-1 could replace the normal depolarization-induced Ca2+ transient in triggering synaptic plasticity.Conclusions: Azid-1 promises to be a useful tool for generating highly controlled spatial and temporal increases of Ca2+ in studies of the many Ca2+-dependent biological processes. Unlike other caged calciums, azid-1 has a substantial cross section or shows a high susceptibility for two-photon photolysis, the only technique that confines the photochemistry to a focal spot that is localized in three dimensions. Azide photolysis could be a useful and more photosensitive alternative to nitrobenzyl photochemistry. 相似文献
18.
Hagen V Bendig J Frings S Wiesner B Schade B Helm S Lorenz D Kaupp UB 《Journal of photochemistry and photobiology. B, Biology》1999,53(1-3):91-102
New caged derivatives of hydrolysis-resistant 8-bromoadenosine cyclic 3',5'-monophosphate (8-Br-cAMP) and 8-bromoguanosine cyclic 3',5'-monophosphate (8-Br-cGMP) are described. The compounds are the axial and equatorial isomers of the (7-methoxycoumarin-4-yl)methyl (MCM) esters of cyclic nucleotides. Synthesis is accomplished by treatment of 4-bromomethyl-7-methoxycoumarin with the tetra-n-butylammonium salts of the 8-bromo-substituted cyclic nucleotides or with the free acids of 8-Br-cAMP and 8-Br-cGMP in the presence of silver(I) oxide. MCM-caged 8-Br-cAMP and MCM-caged 8-Br-cGMP liberate 8-Br-cAMP and 8-Br-cGMP during irradiation with ultraviolet light within a few nanoseconds. They show favorable absorption properties and quantum yields and are resistant to hydrolysis in aqueous buffer solutions. The moderate fluorescence properties of the caged compounds in comparison with the strongly fluorescent 4-hydroxymethyl-7-methoxycoumarin (MCM-OH) photoproduct allow the indirect estimation of the amount of photolytically released cyclic nucleotides in aqueous buffer solutions using fluorescence measurements. Their usefulness for physiological studies has been examined in a mammalian cell line expressing the cyclic nucleotide-gated ion channel of bovine olfactory sensory neurons using the patch-clamp technique and confocal laser scanning microscopy. The caged compounds serve as efficient and rapid intracellular sources of 8-Br-cAMP and 8-Br-cGMP. However, at least in HEK 293 cells, fluorescence signals cannot be used to monitor the photolysis of MCM-caged 8-Br-cAMP and 8-Br-cGMP, due to quenching of the fluorescence of MCM-OH. 相似文献
19.
Fedoryak OD Sul JY Haydon PG Ellis-Davies GC 《Chemical communications (Cambridge, England)》2005,(29):3664-3666
We have synthesized a biologically inert, photosensitive derivative of the major excitatory amino acid, L-glutamate (which we call MDNI-glu) that makes more efficient use of incident light than all other caged glutamates. Laser flash photolysis of MDNI-glu in acutely isolated hippocampal brain slices evoked a rapid increase in intracellular Ca2+ concentration in astrocytes. 相似文献
20.
Synthesis, photochemistry and photorelease properties of 7-methoxy-3-nitro-2-naphthalenemethanol (MNNM) are described. Photoirradiation (?370 nm) of MNNM covalently linked to hippuric acid causes efficient release (∼90%) of hippuric acid. 相似文献