Photochemical‐like Behaviour of Riboflavin in the Dark Promoted by Enzyme‐generated Triplet Acetone

Rojas, Jorge; Silva, Eduardo

doi:10.1111/j.1751-1097.1988.tb02753.x

Cited by 17 publications

(5 citation statements)

References 23 publications

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“…On the other hand, the noncovalent bonding of flavins to DNA (47,48) and to nitrogenated bases (49) has been also described. All these data support the possibility that both Trp and RF can concentrate in the nuclear zone and, accordingly, facilitate the formation of adducts mediated by excitation of RF, either enzymatically (22) or by exposure to visible light (18).…”

Section: Discussionsupporting

confidence: 66%

“…It has also been demonstrated that irradiation of lysozyme with visible light in the presence of RF and molecular oxygen not only produces the photooxidation of some amino acid residues of that enzyme but also generates a binding of this sensitizer to Trp residues of this protein (1 9,20). It is noteworthy that the RF-lysozyme and RF-Trp binding have also been obtained in the dark (21,22).…”

Section: Introductionmentioning

confidence: 99%

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Development of Monoclonal Antibodies Against a Riboflavin‐Tryptophan Photoinduced Adduct: Reactivity to Eye Lens Proteins*

Diaz

Becker

Ioannes

et al. 1996

Photochem & Photobiology

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We describe here the development of monoclonal antibodies to the hapten tryptophan-riboflavin, generated by irradiation of a solution of bovine serum albumin in the presence of riboflavin. The specificity of the three obtained monoclonal antibodies, named 1E6, 5H5, 5A8 all belonging to the IgG1 isotype, was assessed by a competitive enzyme-linked immunosorbent assay in the presence of an increasing concentration of the tryptophan-riboflavin adduct, obtained from an irradiated riboflavin-sensitized tryptophan solution. It was demonstrated that the tryptophan-riboflavin antibodies react with the soluble proteins of the eye lens; this reaction was more intense in the old rat lenses as compared to the young ones, and a maximum binding of the antibodies was obtained with the soluble protein fraction from the human cataractous lens. By indirect immunofluorescence, a reactivity associated with the protein matrix, localized in the lens central zone, was observed. In the peripheral zone of the lens, where the younger cells are found, a marked immunofluorescent emission was observed on structures preferentially localized in the nuclei.

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Section: Discussionsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Development of Monoclonal Antibodies Against a Riboflavin‐Tryptophan Photoinduced Adduct: Reactivity to Eye Lens Proteins*

Diaz

Becker

Ioannes

et al. 1996

Photochem & Photobiology

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“…The induction of flavin photochemistry in the dark, previously attested to by the formation of a riboflavin-lysozyme adduct, has now been expanded by Rojas and Silva (1988). The riboflavin dimer and a product of the lumichrome type are also formed.…”

Section: Peroxidase Systemsmentioning

confidence: 98%

PHOTOCHEMISTRY and PHOTOBIOLOGY WITHOUT LIGHT

Cilento

Adam

1988

Photochem & Photobiology

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Abstract-This review covers the literature since 1980 on chemically and enzymatically generated electronically excited species. The emphasis lies on triplet states of carbonyl products that are derived from dioxetanes and dioxetanones as precursors or from suitable enzymatic oxygenations. Singlet oxygen. an important excited state species in biological processes, is not explicitly treated. The utilization of triplet excited carbonyl products to promote photochemical and photobiological transformations by energy transfer are of primordial interest and not the photomechanistic behavior, photophysical properties and inherent photochemical reactions of such excited state species. Thus, the coverage concentrates on photodamage of DNA and RNA., the photochemistry of favins, vitamin D, tryptophan, arachidonic acid, chlorophyll, lipid peroxidation, urocanase activation, excitation of chlorophlasts, and the aerobic oxidation of Schiff bases derived from amino acids and proteins. The potential perspectives of employing authentic dioxetanes and enzymatically generated dioxetane intermediates as effective photon equivalents in photochemotherapy, phototoxicity, photoaffinity labeling and photogenotoxicity are pointed out, in the hope of stimulating more intensive activity in this emerging and novel bioorganic and photobiological field.

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“…O estado excitado de flavina triplete também pode ser alcançado em ausência de luz por um mecanismo enzimático mediado por peroxidases 39 , o que explica a ocorrência de efeitos citotóxicos promovidos pela riboflavina não irradada 22 .…”

Section: Riboflavina: Um Fotossensibilizador Biológico Eficienteunclassified

Riboflavina: uma vitamina multifuncional

et al. 2005

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Recebido em 17/8/04; aceito em 5/11/04; publicado na web em 13/4/05 RIBOFLAVIN: A MULTIFUNCTIONAL VITAMIN. Riboflavin, a component of the B 2 vitaminic complex, plays important roles in biochemistry, especially in redox reactions, due to the ability to participate in both one-and two-electron transfers as well as acting as a photosensitizer. Accordingly, low intakes of this vitamin have been associated with different diseases, including cancer and cardiovascular diseases. Riboflavin is thought to contribute to oxidative stress through its capacity to produce superoxide but, interestingly, it can also promote the reduction of hydroperoxides. This peculiar and multifunctional behavior allows riboflavin to take part in various biochemical pathways as a nucleophile and an electrophile, turning it into a versatile and important biological compound.Keywords: riboflavin; electron transfer; oxidative stress. INTRODUÇÃOA riboflavina foi isolada (apesar de não purificada) pela primeira vez em 1879 pelo químico inglês A. Wynter Blyth. Em seus estudos relacionados à composição do leite de vaca ele relatara a identificação de um pigmento amarelo brilhante que chamou de "lactocromo" e que hoje nós conhecemos como sendo a riboflavina. Depois desse anúncio, quase cinqüenta anos se passaram até que algum avanço significativo ocorresse com o recém descoberto pigmento amarelo-laranja. Então, ao final dos anos 20 e início da dé-cada de 30 do século XX, uma grande evolução científica aconteceu e pigmentos amarelos semelhantes com um brilho esverdeado fluorescente foram isolados de uma ampla variedade de fontes 1 . O interesse por eles tornou-se ainda maior quando o tal pigmento amarelo foi reconhecido como sendo um constituinte da vitamina do complexo B, sendo a purificação da própria vitamina amplamente facilitada uma vez que se percebeu que o potencial vitamínico estava intimamente correlacionado à fluorescência da riboflavina. Alguns dos principais químicos da época como Richard Kuhn, em Heidelberg, e Paul Karrer, em Zurich, entraram em uma corrida acirrada para determinar a estrutura, bem como para prová-la através de síntese química, sendo que ambos obtiveram sucesso neste intento quase que concomitantemente. Vários nomes foram propostos para o então caracterizado composto, tais como lactoflavina e ovoflavina a fim de estabelecer correlação com a fonte através da qual o composto havia sido isolado. Mas o prefixo ribo foi consagrado no nome pelo qual conhecemos o composto atualmente, por causa da cadeia ribitil e da cor amarela característica proveniente do sistema π conjugado nos anéis isoaloxazina [1][2][3] . RIBOFLAVINA E SUAS FUNÇÕES BIOLÓGICASA riboflavina, 7,8-dimetil-10-ribitil-isoaloxazina, é uma vitamina hidrossolúvel pertencente ao complexo vitamínico B 2 , apresenta coloração amarela e é fluorescente. Além do leite que, como mencionado, foi uma das primeiras fontes de obtenção, a riboflavina é encontrada também em carne, peixe e, principalmente, em vegetais de cor verde-escura 4 . A riboflavina proveniente da dieta en...

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Photochemical‐like Behaviour of Riboflavin in the Dark Promoted by Enzyme‐generated Triplet Acetone

Cited by 17 publications

References 23 publications

Development of Monoclonal Antibodies Against a Riboflavin‐Tryptophan Photoinduced Adduct: Reactivity to Eye Lens Proteins*

Development of Monoclonal Antibodies Against a Riboflavin‐Tryptophan Photoinduced Adduct: Reactivity to Eye Lens Proteins*

PHOTOCHEMISTRY and PHOTOBIOLOGY WITHOUT LIGHT

Riboflavina: uma vitamina multifuncional

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