The photodynamic and non-photodynamic actions of porphyrins
Porphyrias are a family of inherited diseases, each associated with a partial defect in one of the enzymes of the heme biosynthetic pathway. In six of the eight porphyrias described, the main clinical manifestation is skin photosensitivity brought about by the action of light on porphyrins, which ar...
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todo:paper_0100879X_v32_n3_p255_Afonso2023-10-03T14:57:18Z The photodynamic and non-photodynamic actions of porphyrins Afonso, S.C. Enríquez De Salamanca, R. Del C. Batlle, A.M. Photodynamic Porphyrias Porphyrins Protein alterations enzyme heme hemoprotein photosensitizing agent porphyrin protoporphyrin reactive oxygen metabolite uroporphyrin chemically induced disorder darkness human light metabolism porphyria radiation exposure review skin disease ultraviolet radiation Darkness Enzymes Heme Hemeproteins Humans Light Photosensitizing Agents Porphyrias Porphyrins Protoporphyrins Reactive Oxygen Species Skin Diseases Ultraviolet Rays Uroporphyrins Porphyrias are a family of inherited diseases, each associated with a partial defect in one of the enzymes of the heme biosynthetic pathway. In six of the eight porphyrias described, the main clinical manifestation is skin photosensitivity brought about by the action of light on porphyrins, which are deposited in the upper epidermal layer of the skin. Porphyrins absorb light energy intensively in the UV region, and to a lesser extent in the long visible bands, resulting in transitions to excited electronic states. The excited porphyrin may react directly with biological structures (type J reactions) or with molecular oxygen, generating excited singlet oxygen (type II reactions). Besides this well-known photodynamic action of porphyrins, a novel light-independent effect of porphyrins has been described. Irradiation of enzymes in the presence of porphyrins mainly induces type I reactions, although type II reactions could also occur, further increasing the direct non-photodynamic effect of porphyrins on proteins and macromolecules. Conformational changes of protein structure are induced by porphyrins in the dark or under UV light, resulting in reduced enzyme activity and increased proteolytic susceptibility. The effect of porphyrins depends not only on their physico-chemical properties but also on the specific site on the protein on which they act. Porphyrin action alters the functionality of the enzymes of the heme biosynthetic pathway exacerbating the metabolic deficiencies in porphyrias. Light energy absorption by porphyrins results in the generation of oxygen reactive species, overcoming the protective cellular mechanisms and leading to molecular, cell and tissue damage, thus amplifying the porphyric picture. Fil:Del C. Batlle, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0100879X_v32_n3_p255_Afonso |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Photodynamic Porphyrias Porphyrins Protein alterations enzyme heme hemoprotein photosensitizing agent porphyrin protoporphyrin reactive oxygen metabolite uroporphyrin chemically induced disorder darkness human light metabolism porphyria radiation exposure review skin disease ultraviolet radiation Darkness Enzymes Heme Hemeproteins Humans Light Photosensitizing Agents Porphyrias Porphyrins Protoporphyrins Reactive Oxygen Species Skin Diseases Ultraviolet Rays Uroporphyrins |
| spellingShingle |
Photodynamic Porphyrias Porphyrins Protein alterations enzyme heme hemoprotein photosensitizing agent porphyrin protoporphyrin reactive oxygen metabolite uroporphyrin chemically induced disorder darkness human light metabolism porphyria radiation exposure review skin disease ultraviolet radiation Darkness Enzymes Heme Hemeproteins Humans Light Photosensitizing Agents Porphyrias Porphyrins Protoporphyrins Reactive Oxygen Species Skin Diseases Ultraviolet Rays Uroporphyrins Afonso, S.C. Enríquez De Salamanca, R. Del C. Batlle, A.M. The photodynamic and non-photodynamic actions of porphyrins |
| topic_facet |
Photodynamic Porphyrias Porphyrins Protein alterations enzyme heme hemoprotein photosensitizing agent porphyrin protoporphyrin reactive oxygen metabolite uroporphyrin chemically induced disorder darkness human light metabolism porphyria radiation exposure review skin disease ultraviolet radiation Darkness Enzymes Heme Hemeproteins Humans Light Photosensitizing Agents Porphyrias Porphyrins Protoporphyrins Reactive Oxygen Species Skin Diseases Ultraviolet Rays Uroporphyrins |
| description |
Porphyrias are a family of inherited diseases, each associated with a partial defect in one of the enzymes of the heme biosynthetic pathway. In six of the eight porphyrias described, the main clinical manifestation is skin photosensitivity brought about by the action of light on porphyrins, which are deposited in the upper epidermal layer of the skin. Porphyrins absorb light energy intensively in the UV region, and to a lesser extent in the long visible bands, resulting in transitions to excited electronic states. The excited porphyrin may react directly with biological structures (type J reactions) or with molecular oxygen, generating excited singlet oxygen (type II reactions). Besides this well-known photodynamic action of porphyrins, a novel light-independent effect of porphyrins has been described. Irradiation of enzymes in the presence of porphyrins mainly induces type I reactions, although type II reactions could also occur, further increasing the direct non-photodynamic effect of porphyrins on proteins and macromolecules. Conformational changes of protein structure are induced by porphyrins in the dark or under UV light, resulting in reduced enzyme activity and increased proteolytic susceptibility. The effect of porphyrins depends not only on their physico-chemical properties but also on the specific site on the protein on which they act. Porphyrin action alters the functionality of the enzymes of the heme biosynthetic pathway exacerbating the metabolic deficiencies in porphyrias. Light energy absorption by porphyrins results in the generation of oxygen reactive species, overcoming the protective cellular mechanisms and leading to molecular, cell and tissue damage, thus amplifying the porphyric picture. |
| format |
JOUR |
| author |
Afonso, S.C. Enríquez De Salamanca, R. Del C. Batlle, A.M. |
| author_facet |
Afonso, S.C. Enríquez De Salamanca, R. Del C. Batlle, A.M. |
| author_sort |
Afonso, S.C. |
| title |
The photodynamic and non-photodynamic actions of porphyrins |
| title_short |
The photodynamic and non-photodynamic actions of porphyrins |
| title_full |
The photodynamic and non-photodynamic actions of porphyrins |
| title_fullStr |
The photodynamic and non-photodynamic actions of porphyrins |
| title_full_unstemmed |
The photodynamic and non-photodynamic actions of porphyrins |
| title_sort |
photodynamic and non-photodynamic actions of porphyrins |
| url |
http://hdl.handle.net/20.500.12110/paper_0100879X_v32_n3_p255_Afonso |
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