74362-46-2Relevant academic research and scientific papers
Bacteriochlorophyll/imidazole and chlorophyll/imidazole complexes are negatively charged in an apolar environment
Alia,Matysik,Erkelens,Hulsbergen,Gast,Lugtenburg,De Groot
, p. 325 - 330 (2000)
600 MHz 15N-NMR and 2D homonuclear 1H-1H and heteronuclear 1H-15N-NMR data for bacteriochlorophyll a/imidazole and chlorophyll a/imidazole have been recorded. Unambiguous assignments of the 15N signals of the two nitrogens of imidazole ligated to the Mg of the bacteriochlorophyll a or chlorophyll a were obtained. It follows that the imidazole in complex is deprotonated, which implies that the chlorophyll/imidazole carries a full negative charge in the apolar solvent environment. This information is potentially useful in characterizing the nature of the magnesium-histidine interaction and the charge state of chlorophylls coordinated by histidine in photosynthetic pigment protein complexes.
15N NMR Hyperpolarization of Radiosensitizing Antibiotic Nimorazole by Reversible Parahydrogen Exchange in Microtesla Magnetic Fields
Salnikov, Oleg G.,Chukanov, Nikita V.,Svyatova, Alexandra,Trofimov, Ivan A.,Kabir, Mohammad S. H.,Gelovani, Juri G.,Kovtunov, Kirill V.,Koptyug, Igor V.,Chekmenev, Eduard Y.
, p. 2406 - 2413 (2021)
Nimorazole belongs to the imidazole-based family of antibiotics to fight against anaerobic bacteria. Moreover, nimorazole is now in Phase 3 clinical trial in Europe for potential use as a hypoxia radiosensitizer for treatment of head and neck cancers. We envision the use of [15N3]nimorazole as a theragnostic hypoxia contrast agent that can be potentially deployed in the next-generation MRI-LINAC systems. Herein, we report the first steps to create long-lasting (for tens of minutes) hyperpolarized state on three 15N sites of [15N3]nimorazole with T1 of up to ca. 6 minutes. The nuclear spin polarization was boosted by ca. 67000-fold at 1.4 T (corresponding to P15N of 3.2 %) by 15N?15N spin-relayed SABRE-SHEATH hyperpolarization technique, relying on simultaneous exchange of [15N3]nimorazole and parahydrogen on polarization transfer Ir-IMes catalyst. The presented results pave the way to efficient spin-relayed SABRE-SHEATH hyperpolarization of a wide range of imidazole-based antibiotics and chemotherapeutics.
Solution structure of a DNA double helix with consecutive metal-mediated base pairs
Johannsen, Silke,Megger, Nicole,Boehme, Dominik,Sigel, Roland K. O.,Mueller, Jens
, p. 229 - 234 (2010)
Metal-mediated base pairs represent a powerful tool for the site-specific functionalization of nucleic acids with metal ions. The development of applications of the metal-modified nucleic acids will depend on the availability of structural information on these double helices. We present here the NMR solution structure of a self-complementary DNA oligonucleotide with three consecutive imidazole nucleotides in its centre. In the absence of transition-metal ions, a hairpin structure is adopted with the artificial nucleotides forming the loop. In the presence of Ag(i) ions, a duplex comprising three imidazoleg-Ag+ g-imidazole base pairs is formed. Direct proof for the formation of metal-mediated base pairs was obtained from 1J(15 N, 107/109 Ag) couplings upon incorporation of 15N-labelled imidazole. The duplex adopts a B-type conformation with only minor deviations in the region of the artificial bases. This work represents the first structural characterization of a metal-modified nucleic acid with a continuous stretch of metal-mediated base pairs.
pH Dependence of 15N NMR Shifts and Coupling Constants in Aqueous Imidazole and 1-Methylimidazole. Comments on Estimation of Tautomeric Equilibrium Constants for Aqueous Histidine
Alei, M.,Morgan, L. O.,Wageman, W. E.,Whaley, T. W.
, p. 2881 - 2887 (1980)
15N, 1H, and 13C NMR spectra for imidazole and -1-methylimidazole in aqueous solution as functions of pH provide shift and coupling constant information useful in characterizing the protonated and unprotonated forms of these compounds and as background for determining N binding to other species, such as metal ions.When combined with similar data for the imidazole-ring atoms in histidine, these data give more reliable estimates of tautomeric equilibrium constants for the amphionic and anionic forms of histidine than were possible from the histidine data alone.
Experimental and Computational Evidence for a Loose Transition State in Phosphoroimidazolide Hydrolysis
Li, Li,Lelyveld, Victor S.,Prywes, Noam,Szostak, Jack W.
supporting information, p. 3986 - 3989 (2016/05/19)
Phosphoroimidazolides play a critical role in several enzymatic phosphoryl transfer reactions and have been studied extensively as activated monomers for nonenzymatic nucleic acid replication, but the detailed mechanisms of these phosphoryl transfer reactions remain elusive. Some aspects of the mechanism can be deduced by studying the hydrolysis reaction, a simpler system that is amenable to a thorough mechanistic treatment. Here we characterize the transition state of phosphoroimidazolide hydrolysis by kinetic isotope effect (KIE) and linear free energy relationship (LFER) measurements, and theoretical calculations. The KIE and LFER observations are best explained by calculated loose transition structures with extensive scissile bond cleavage. These three-dimensional models of the transition state provide the basis for future mechanistic investigations of phosphoroimidazolide reactions.
