- UVA photoinduced yeast protein modifications by methylene blue and naproxen
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UVA photosensitization by methylene blue (MB) or by naproxen (NAP) towards cell proteins in yeast Saccharomyces cerevisiae was investigated in order to compare this system with two simpler models, such as free Trp in solution and as a component of bovine and human serum albumin. The process was studied by monitoring protein tryptophan (Trp) residue integrity. The sensitized photodegradation of proteins resulted in different degrees of Trp damage with different Trp (photo)-products. Indeed, many of these Trp derivatives are diagnostic for the photosensitization mechanism and some of them were obtained from cells by UVA photosensitization for the first time in this work. The analysis of quantum yields of photoproduct distribution allowed us to weigh up the type I/II contribution on a UVA photosensitization mechanism. The UVA mediated generation of these Trp derivatives is consistent with the occurrence of singlet oxygen formation (almost dominant in MB), and photoionization (significant in NAP) within the protein matrix. The results obtained in the case of this more complex system (cell) are in agreement with the two simpler models recently studied in our lab. The quantum yields of Trp photoinduced degradation, as well as of its photoproducts formation, decrease with increasing the complexity of the investigated target. The Royal Society of Chemistry and Owner Societies 2013.
- Bracchitta, Giuseppina,Catalfo, Alfio,De Guidi, Guido
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p. 967 - 973
(2013/09/12)
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- Composition for Topical Use
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The use, as a dermatological or cosmetic medicament, of compounds capable of transiently interacting with the AhR receptor (aryl hydrocarbon receptor) as agents for modulating skin functions such as sebaceous function, skin healing, skin atrophy termed “dermatoporosis”, estrogen deprivation and defense against infection, without inducing other toxic effects of the TCDD type. The compounds that interact with the AhR receptor are chosen in that they have a metabolism favorable to the dissociation of these effects, in particular by virtue of in situ production from a precursor and/or metabolization modulated in situ.
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- PHOTOOXIDATION OF L(-)-TRYPTOPHAN BY URANYL IONS
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The uranyl-sensitized photodecomposition of L(-)-tryptophan has been carried out.Kynurenin and N-formylkynurenin have been characterized as the products of photooxidation of L(-)-tryptophan, and a tentative mechanism for the photooxidation af L(-)-tryptophan has been proposed.
- Bhatt, Rachana,Shrimali, P. S.,Ameta, S. C.,Chowdhry, H. C.
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p. 388 - 390
(2007/10/02)
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- CERTAIN RELATIONSHIPS OF FORMATION OF THE PRODUCTS OF OZONIZATION OF TRYPTOPHAN.
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In order to elucidate the role of radical reactions in ozonization of tryptophan, the authors carried out a comparative study of ozonization and radiolysis of tryptophan in dilute aqueous solutions, and also of its oxidation by OH radicals generated in the Fenton reaction. Formation of products of decomposition, polymerization, and deamination of the amino acid was observed during ozonization of tryptophan. As in the case of radiolysis and oxidation by Fenton's reagent, an important part in the formation of final products of tryptophan ozonization in aqueous solution is played by homolytic processes involving OH radicals.
- Sikorskaya,Ignatenko,Cherenkevich
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p. 1910 - 1914
(2007/10/02)
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