کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9890010 | 1539997 | 2005 | 18 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Opposite effects of peroxidase in the initial stages of tyrosinase-catalysed melanin biosynthesis
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کلمات کلیدی
EOXPODDopachromeDiphenolPPOTBCROS - ROSHydrogen peroxide - آب اکسیژنهAntioxidant - آنتی اکسیدانUltraviolet radiation - اشعه ماوراء بنفشRadical - افراطیOxygen - اکسیژنCompound I - ترکیب ICompound II - ترکیب دومTyrosinase - تیروزیناز Lag period - دوره لاغرSOD - سدSuperoxide dismutase - سوکسوکس دیسموتازFluorescence - فلورسنسMelanogenesis - ملانوژنزmelanin - ملانینMonophenol - مونوفنولH2O2 - هیدروژن پراکسیدPeroxidase - پراکسیدازQuinone - کینون Reactive oxygen species - گونههای فعال اکسیژن
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
زیست شیمی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The tyrosinase/oxygen enzymatic system catalyses the orthohydroxylation of l-tyrosine to l-dopa and the oxidation of this to dopaquinone, which evolves non-enzymatically towards to form melanins. The literature has demonstrated and revised the existence of peroxidase/hydrogen peroxide in the melanosomas of skin melanocytes, but points to controversy concerning the effects on melanogenesis. Some authors have recently proposed a new physiological function for tyrosinase, namely the direct scavenging of tyrosyl radicals, which are toxic oxidants of melanocytes. In this contribution, we describe and interpret four effects of peroxidase/hydrogen peroxide on melanogenesis. Two of these effects are its antagonism and synergy as regards the monophenolase and diphenolase activities, respectively, of tyrosinase/oxygen in the initial steps that trigger melanogenesis. Another effect concerns the increase in the oxidant character of the medium in the melanosome by increasing the synthesis of oxidising quinones (o-dopaquinone, p-topaquinone, dopachrome) and the consumption of antioxidant diphenols (l-dopa), which are intermediate biomolecules in melanogenesis. Lastly, we demonstrate that the tyrosyl radicals generated by light or by the peroxidase/hydrogen peroxide system are not directly trapped by the tyrosinase but by the antioxidant orthodiphenol, l-dopa, accumulated in the steady-state of melanogenesis. In conclusion, peroxidase/hydrogen peroxide may help regulate the development of melanogenesis and the oxidant environment within the melanosome. This enzyme deserves further study for its possible antitumoral and depigmentation capacities in skin cancer and hyperpigmentation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: The International Journal of Biochemistry & Cell Biology - Volume 37, Issue 6, June 2005, Pages 1179-1196
Journal: The International Journal of Biochemistry & Cell Biology - Volume 37, Issue 6, June 2005, Pages 1179-1196
نویسندگان
Francisco GarcÃa-Molina, Lorena G. Fenoll, Julio C. Morote, Pedro A. GarcÃa-Ruiz, José N. RodrÃguez-López, Francisco GarcÃa-Cánovas, José Tudela,