PHOTOREACTIVATING ENZYME FROM <i>Streptomyces griseus</i>—VI. ACTION SPECTRUM AND KINETICS OF PHOTOREACTIVATION

Eker, A.P.M.; Hessels, J.K.C.; Dekker, R. H.

doi:10.1111/j.1751-1097.1986.tb03586.x

Cited by 59 publications

(38 citation statements)

References 40 publications

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“…[10,15,16] The results seem to support previous findings that the photolyase may provide a hydrophobic environment for the substrate (dimer). [8,17] However, an inverse solvent dependence was observed in covalently linked flavin-dimer systems by Carell and coworkers. [11,18] By taking two sets of measurements in water/ ethylene glycol mixtures and various organic solvents, they observed increased splitting efficiencies in polar solvents.…”

Section: Introductionmentioning

confidence: 92%

Efficient Photosensitized Splitting of Thymine Dimer by a Covalently Linked Tryptophan in Solvents of High Polarity

et al. 2005

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Keywords: DNA photorepair / Electron transfer / Pyrimidine dimer / Tryptophan / Solvent effectsTryptophan-thymine dimer model compounds used to mimic the repair reaction of DNA photolyase have been synthesized. The photosensitized cleavage of the dimer by the covalently linked tryptophan is strongly solvent-dependent with the reaction rates increasing in increasingly polar solvents, for example, the quantum yield Φ = 0.004 in THF/hexane (5:95) and 0.093 in water. The fluorescence of the tryptophan residue is quenched by the dimer moiety by electron transfer from the excited tryptophan to the dimer. Fluorescence-quenching studies indicated that the electron transfer was efficient in polar solvents. The splitting efficiency of the dimer radical anion within the tryptophan ·+ -dimer ·-species is also remarkably solvent-dependent and increases with the

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Section: Introductionmentioning

confidence: 92%

Efficient Photosensitized Splitting of Thymine Dimer by a Covalently Linked Tryptophan in Solvents of High Polarity

et al. 2005

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“…Photolyases from a variety of species have been characterized (Sabourin and Ley, 1988;Eker et al, 1986;Johnson and Haynes, 1986;Sancar et al, 1984). All known photolyases utilize two noncovalently bound cofactors as sensitizers, one of which is the dihydroflavin FADH2 (Wang and Jorns, 1989;Wang et al, 1988;Payne et al, 1987;Eker et al, 1986). Two classes of photolyases are distinguished on the basis of the identity of the second chromophore, which is either 5,10-methenyltetrahydrofolate or a deazaflavin.…”

Section: Introductionmentioning

confidence: 99%

Solvent Dependence of Pyrimidine Dimer Splitting in a Covalently Linked Dimer‐indole System

Kim

Hartman

Rose

1990

Photochem & Photobiology

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Abstract— –Cyclobutadipyrimidines (pyrimidine dimers) undergo splitting that is photosensitized by indole derivatives. We have prepared a compound in which a two‐carbon linker connects a dimer to an indolyl group. Indolyl fluorescence quenching indicated that the two portions of the molecule interact in the excited state. Intramolecular photosensitization of dimer splitting was remarkably solvent dependent, ranging from φspl= 0.06 in water to a high value of φspl= 0.41 in the least polar solvent mixture examined, l,4‐dioxane‐isopentane(5: 95). A derivative with a 5‐methoxy substituent on the indolyl ring behaved similarly. These results have been interpreted in terms of electron transfer from the excited indolyl group to the dimer, which would produce a charge‐separated species. The dimer anion within such a species could split or undergo back electron transfer. The possibility that back electron transfer is in the Marcus inverted region can be used to rationalize the observed solvent dependence of splitting. In the inverted region, the high driving force of a charge recombination exceeds the reorganization energy of the solvent, which is less for solvents of low polarity than those of high polarity. If this theory is applicable to the hypothetical charge‐separated species, a slower back electron transfer, and consequently higher splitting efficiencies, would be expected in solvents of lower polarity. Photolyases may have evolved in which a low polarity active site retards back transfer of an electron and thereby contributes to the efficiency of the enzymatic dimer splitting.

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“…One deazaflavin, 7,8-didemethyl-8-hydroxy-5-deazaflavin, has a ribitylated derivative known as coenzyme F 0 , and an oligoglutamylated derivative of F 0 (coenzyme F 420 ) (Fig. 1D) is involved in hydride transfer during reductive transformation of carbon dioxide and acetate into methane in methanogenic archaea (103,151,258,299,514). Coenzyme F 420 has also been found in certain streptomycetes, in which it serves as a cofactor in the biosynthesis of tetracycline and lincomycin (74,189,347,369).…”

Section: Other Natural Flavinsmentioning

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

325

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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PHOTOREACTIVATING ENZYME FROM Streptomyces griseus—VI. ACTION SPECTRUM AND KINETICS OF PHOTOREACTIVATION

Cited by 59 publications

References 40 publications

Efficient Photosensitized Splitting of Thymine Dimer by a Covalently Linked Tryptophan in Solvents of High Polarity

Efficient Photosensitized Splitting of Thymine Dimer by a Covalently Linked Tryptophan in Solvents of High Polarity

Solvent Dependence of Pyrimidine Dimer Splitting in a Covalently Linked Dimer‐indole System

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

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