Reactivity studies of roseoflavin analogues: a correlation between reactivity and absorption maxima

Shinkai, Seiji; Kameoka, Kei; Honda, Noriaki; Ueda, Kaori; Manabe, Osamu

doi:10.1039/c39850000673

Cited by 14 publications

(21 citation statements)

References 3 publications

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“…Cryptand 5 : It has previously been shown by Shinkai17a that the cation binding constant can be determined kinetically for systems similar to the one described in Scheme by using Equation (9), established previously by Connors and co‐workers 17b. This relationship is valid for the formation of a 1:1 complex under [M + ]≫[ 2 ], in which k obs is the observed rate constant at a particular concentration of cation [M + ] and ( K c ) is the binding constant for the cryptand, the equilibrium being established faster than the dissociation processes.…”

Section: Resultsmentioning

confidence: 85%

Photoinduced Formation of a Cryptand from a Coronand: An Unexpected Switch in Cation Binding Affinity

McSkimming¹,

Tucker²,

Bouas‐Laurent³

et al. 2002

Chem. Eur. J.

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Aza‐crown ethers 2 and 3 with anthracene‐containing pendant arms have been synthesised and characterised. Both compounds bind Group 1 metal cations in solution, forming complexes of 1:1 stoichiometry. The properties of compound 2 and its complexes have been studied by a range of techniques, including NMR, UV and fluorescence spectroscopy and X‐ray crystallography. The pendant arms can adopt either a cis or a trans geometry, the cis geometry favoured with larger cations. The geometry of the complex affects the fluorescence properties of the system, with larger cations giving higher excimer/monomer ratios. Upon irradiation at λ>300 nm, coronand 2 forms the cryptand 5 through a reversible intramolecular [4π+4π] cycloaddition reaction. The rates of the forward and reverse reactions of this photochromic process are cation dependent; in particular the rate of the thermal reverse reaction is decreased by smaller cations and increased by larger cations, especially Rb+. The metal binding constants in methanol for 2 and 5 have been determined, revealing that the cryptand 5 binds Na+ and Rb+ more weakly than crown ether 2 by over two orders of magnitude.

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Section: Resultsmentioning

confidence: 85%

Photoinduced Formation of a Cryptand from a Coronand: An Unexpected Switch in Cation Binding Affinity

McSkimming¹,

Tucker²,

Bouas‐Laurent³

et al. 2002

Chem. Eur. J.

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“…10 Accordingly, the polarity of the solvent is one of the main determinants of the extent of charge transfer in RoF. 10,32 Solutions of RoF are red in polar solvents, indicating enhanced internal charge transfer, and yellow to orange with a strong green fluorescence in nonpolar solvents that tend to suppress internal charge transfer. 10,29,32,33 Donor−acceptor (D−A, or push−pull) molecules form a large family of chromophores.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Intramolecular Charge Transfer in an Electronically Modified Flavin Derivative: Roseoflavin

Karasulu

Thiel

2014

J. Phys. Chem. B

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The photophysical properties of a push-pull flavin derivative, roseoflavin (RoF), are investigated in different surroundings at the molecular level, with focus on intramolecular charge transfer (ICT). Time-dependent density functional theory (TD-DFT, CAM-B3LYP functional) and DFT-based multireference configuration interaction (DFT/MRCI) are used to compute excited-state energies and one-electron properties of a truncated RoF model, roseolumiflavin (RoLF). Solvent effects are taken into account implicitly by the conductor-like polarizable continuum model and explicitly through a microsolvation scheme. In the gas phase, the calculations predict no crossing between the lowest locally excited (LE) and charge-transfer (CT) states upon twisting the dimethylamine donor group relative to the plane of the isoalloxazine acceptor moiety, whereas this crossing is found to be facile in solution (i.e., in water or benzene). Crossing of the LE and CT states facilitates ICT, which is the main cause of the fluorescence quenching and dual fluorescence character experimentally observed for roseoflavin in solution. The barrier for the ICT process is computed to be lower in water than in benzene, consistent with the enhanced ICT rates observed in more polar solvents. We present a detailed study of the molecular mechanism of the photoinduced ICT process in RoLF. For a typical donor-acceptor chromophore, three such mechanisms are discussed in the literature, which differ in the alignment of the donor and acceptor planes, namely, planar ICT (PICT), perpendicular-twisted ICT (TICT), and wagging ICT (WICT). Our theoretical results suggest that the TICT mechanism is favored in RoLF.

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“…Intracellular roseoflavin is converted by RF kinase to roseoflavin-5Ј-phosphate (an analog of FMN) and further by FAD synthetase to roseoflavin adenine dinucleotide (515). Roseoflavin derivatives of FMN and FAD are inactive as coenzymes, apparently due to loss of their oxidizing ability following an intramolecular charge transfer from the 8-dimethylamino group to the pteridine moiety (434). Roseoflavin producers normally convert roseoflavin to analogs of FMN and FAD, so presumably defects in these conversions cannot explain S. davawensis resistance to roseoflavin (155).…”

Section: Roseoflavinmentioning

confidence: 99%

Genetic Control of Biosynthesis and Transport of Riboflavin and Flavin Nucleotides and Construction of Robust Biotechnological Producers

Abbas

Sibirny

2011

Microbiol Mol Biol Rev

316

272

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SUMMARY Riboflavin [7,8-dimethyl-10-(1′- d -ribityl)isoalloxazine, vitamin B 2 ] is an obligatory component of human and animal diets, as it serves as the precursor of flavin coenzymes, flavin mononucleotide, and flavin adenine dinucleotide, which are involved in oxidative metabolism and other processes. Commercially produced riboflavin is used in agriculture, medicine, and the food industry. Riboflavin synthesis starts from GTP and ribulose-5-phosphate and proceeds through pyrimidine and pteridine intermediates. Flavin nucleotides are synthesized in two consecutive reactions from riboflavin. Some microorganisms and all animal cells are capable of riboflavin uptake, whereas many microorganisms have distinct systems for riboflavin excretion to the medium. Regulation of riboflavin synthesis in bacteria occurs by repression at the transcriptional level by flavin mononucleotide, which binds to nascent noncoding mRNA and blocks further transcription (named the riboswitch). In flavinogenic molds, riboflavin overproduction starts at the stationary phase and is accompanied by derepression of enzymes involved in riboflavin synthesis, sporulation, and mycelial lysis. In flavinogenic yeasts, transcriptional repression of riboflavin synthesis is exerted by iron ions and not by flavins. The putative transcription factor encoded by SEF1 is somehow involved in this regulation. Most commercial riboflavin is currently produced or was produced earlier by microbial synthesis using special selected strains of Bacillus subtilis , Ashbya gossypii , and Candida famata . Whereas earlier RF overproducers were isolated by classical selection, current producers of riboflavin and flavin nucleotides have been developed using modern approaches of metabolic engineering that involve overexpression of structural and regulatory genes of the RF biosynthetic pathway as well as genes involved in the overproduction of the purine precursor of riboflavin, GTP.

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Reactivity studies of roseoflavin analogues: a correlation between reactivity and absorption maxima

Abstract: The absorption spectra of roseoflavin analogues are very sensitive to solvent effect and the oxidising ability (in the photo-oxidation of l-benzyl-l,4-dihydronicotinamide) correlates well with the shift in the absorption maxima.

Cited by 14 publications

References 3 publications

Photoinduced Formation of a Cryptand from a Coronand: An Unexpected Switch in Cation Binding Affinity

Photoinduced Formation of a Cryptand from a Coronand: An Unexpected Switch in Cation Binding Affinity

Photoinduced Intramolecular Charge Transfer in an Electronically Modified Flavin Derivative: Roseoflavin

Genetic Control of Biosynthesis and Transport of Riboflavin and Flavin Nucleotides and Construction of Robust Biotechnological Producers

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