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The behaviour of potential prebiotic species in space is of main concern in the chemistry at the origin of life. Their reactivity or stability in spatial conditions, under strong UV radiations or ion bombardments remains an open question and needs wide investigations. As protons are by far the most abundant ions in space, we focus presently on proton-induced collisions on imid-azole and 2-aminoimidazole evidenced as important prebiotic RNA intermediates. Uncon-strained full optimization of the structures was performed with B3LYP/cc-pVTZ model chem-istry. The calculations were performed in a wide collision energy range in order to model vari-ous astrophysical environments, from eV in the interstellar medium, up to keV for solar winds or supernovae shock-wave protons. Such study drives for the first time a theoretical insight on the influence of the amino substituent on the proton-induced charge transfer. We evaluated besides the role of icy grain environments through a cluster approach modelling the effect of a stepwise microhydration on the process. Comparisons with oxygenated and sulfurated ana-logues address further qualitative trends on the respective stability or reactivity of such heter-ocycles which may be of tremendous interest in prebiotic chemistry. Charge transfer appears effectively quite efficient for imidazole compounds and their sulfurated analogue compared to the oxygenated heterocycle.
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Name: The journal of physical chemistry. A
Cytochrome c oxidase is a membrane-bound redox-driven proton pump, which harbors two proton-transfer pathways, D and K, used at different stages of the reaction cycle. Here, we address the question i...
Inverted region behavior for concerted proton-coupled electron transfer (PCET) was recently demonstrated for biomimetic anthracene-phenol-pyridine molecular triads. Photoexcitation of the anthracene t...
The membrane-protein complex photosystem II (PSII) catalyzes photosynthetic water oxidation. Proton transfer plays an integral role in the catalytic cycle of water oxidation by maintaining charge bala...
The proton transfer of 3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazole (bis-HPTA), a fluorophore proficient in self-aided twin proton transfer, has been explored in the presence of dimethylformamide (DMF)....
[Ru(Rtpy)(bpy)(HO)] (; bpy = 2,2'-bipyridine, and Rtpy = 2,2':6',2″-terpyridine derivatives) complexes with a variety of 4'-substituent groups on Rtpy were synthesized and characterized to reveal th...
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...
OBJECTIVES: I. Determine the effects of aminoimidazole carboxamide riboside (AICAR) on hematologic manifestations of Lesch-Nyhan disease. II. Assess the behavioral and neurological bene...
This phase I trial studies the side effects and best dose of hypofractionated proton beam radiation therapy when given together with paclitaxel and carboplatin in treating patients with st...
the aim of the study is to assess the role of indomethacin in cases of difficult embryo transfer in intracytoplasmic sperm injection cycles.
Malignant gliomas are the most common and deadly primary brain tumors in adults. The clinical outcome of patients with glioblastoma depends on key molecular genetic alteration. Specificall...
Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.
An imidazole derivative which is a metabolite of the antineoplastic agents BIC and DIC. By itself, or as the ribonucleotide, it is used as a condensation agent in the preparation of nucleosides and nucleotides. Compounded with orotic acid, it is used to treat liver diseases.
An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
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)
An enzyme that, in the course of purine ribonucleotide biosynthesis, catalyzes the conversion of 5'-phosphoribosyl-4-(N-succinocarboxamide)-5-aminoimidazole to 5'-phosphoribosyl-4-carboxamide-5-aminoimidazole and the conversion of adenylosuccinic acid to AMP. EC 126.96.36.199.