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Deprotonated para-coumaric acid is commonly considered as a model for the chromophore in photoactive yellow protein where it undergoes E→Z isomerization following absorption of blue light. Here, tandem ion mobility mass spectrometry is coupled with laser excitation to study the photochemistry of deprotonated para-coumaric acid, to show that the phenoxide and carboxylate forms have distinct photochemical responses with maxima in their action spectra at 430nm and 360nm, respectively. A one-way photoinitiated proton transfer was found to convert the E isomer of the carboxylate deprotomer to the phenoxide deprotomer through a mechanism postulated to involve an excited-state enol-keto tautomerism followed by a series of ground state rearrange- ments including a second proton transfer. This mechanism is supported by experiments in which the intermediate keto isomer was prepared and spectroscopically probed, and through master equation modelling of possible ground state isomerization processes. The Z isomer of the carboxylate deprotomer shows weak Z→E photoisomerization response that occurs in competition with photodestruction (presumably electron de- tachment), demonstrating that the E and Z isomers undergo different processes in their excited states. The study highlights the utility of isomer-selective spectroscopy for characterizing the photochemistry of isolated anions possessing multiple deprotonation sites.
This article was published in the following journal.
Name: The journal of physical chemistry. A
Para-coumaric acid methyl ester (pCAME) is one of the bioactive components of Costus speciosus (Koen) Sm. (Zingiberaceae). This plant is traditionally used in Asia to treat catarrhal fevers, worms, dy...
In this work, the influence of cyanide group substituted on the excited-state intramolecular proton transfer of 2-(2-hydroxyphenyl)benzothiazole (HBT) has been theoretical studied. It is found that th...
We report examples of intramolecular proton transfer reactions to functionalize carbon monoxide and tert-butyl nitrile from a bis(phosphido) thorium complex. The reaction of (C5Me5)2Th[PH(Mes)]2, Mes ...
Flavonoids widely found in natural foods are characterized by acting as antioxidants compounds. There are close relationship between the antiradical activities and structural properties of flavonoids....
ε-caprolactone-p-coumaric acid copolymers at different mole ratios (ε-caprolactone:p-coumaric acid 1:0, 10:1, 8:1, 6:1, 4:1, and 2:1) were synthesized by melt-polycondensation and using 4-dodecylben...
This phase I trial studies the side effects of linear energy transfer (LET) optimized image modulated proton therapy (IMPT) in treating pediatric patients with ependymoma. Radiation therap...
Disequilibrium between acid and base in the inner ear was suggested to be an important factor leading to hearing impairment associated with SLC26A4 mutations. For acid-base homeostasis in ...
Background: Rebound acid hypersecretion and acid-related symptoms after discontinuation of proton-pump inhibitor has been reported in previous studies. In patients with concurrent gastro-e...
Patients with bleeding ulcers identified by endoscopy will be randomly assigned to receive an acid-blocking drug (called a proton pump inhibitor [PPI]) either by mouth every 3 hours for 24...
The gastric acid pocket is believed to be the reservoir from which acid reflux events originate. The risk for acidic reflux is mainly determined by the position of the gastric acid pocket....
Hydroxycinnamic acid and its derivatives. Act as activators of the indoleacetic acid oxidizing system, thereby producing a decrease in the endogenous level of bound indoleacetic acid in plants.
Energy that is generated by the transfer of protons or electrons across an energy-transducing membrane and that can be used for chemical, osmotic, or mechanical work. Proton-motive force can be generated by a variety of phenomena including the operation of an electron transport chain, illumination of a PURPLE MEMBRANE, and the hydrolysis of ATP by a proton ATPase. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed, p171)
A class of phenolic acids related to chlorogenic acid, p-coumaric acid, vanillic acid, etc., which are found in plant tissues. It is involved in plant growth regulation.
Enzymes of the isomerase class that catalyze the transfer of acyl-, phospho-, amino- or other groups from one position within a molecule to another. EC 5.4.
BENZOIC ACID substituted with an amino group. They can either be mono-, di-, or tri- substituted. Para-aminobenzoic acid (see 4-AMINOBENZOIC ACID) is considered a member of the vitamin b complex.
Within medicine, nutrition (the study of food and the effect of its components on the body) has many different roles. Appropriate nutrition can help prevent certain diseases, or treat others. In critically ill patients, artificial feeding by tubes need t...