PHOTOCHEMISTRY OF 5-S-CYSTEINYLDOPA
PHOTOCHEMISTRY OF 5-S-CYSTEINYLDOPA
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DOI：
10.1111/j.1751-1097.1994.tb03939.x
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发表时间：
1994-07-01
影响因子：
3.3
通讯作者：
PROTA, G
中科院分区：
文献类型：
--
作者：
COSTANTINI, C;DISCHIA, M;PROTA, G
研究了黑素细胞代谢的无色产物5-S-半胱氨酰多巴（5-S-CD）在中性磷酸盐缓冲液中的光化学行为。发现5-S-CD暴露于派热克斯过滤的UV光（波长> 320 nm）诱导氧依赖性反应，除了大量的聚合物材料外，还导致苯并噻嗪衍生物I和II（两种非对映异构体）。超氧化物歧化酶对5-S-CD消耗有轻微的抑制作用，而其它活性氧清除剂对反应过程无影响。添加谷胱甘肽作为氢供体完全抑制反应。用UVB光（波长范围280-320 nm）光解5-S-CD主要是形成3，4-二羟基-苯丙氨酸，推测是由S-CH 2键的光均裂随后脱硫而产生的。这些结果与肤色白皙的个体对光化损伤和皮肤癌的高易感性有关。
The photochemical behavior of 5-S-cysteinyldopa (5-S-CD), a colorless product of melanocyte metabolism, was investigated in neutral phosphate buffer with biologically relevant UV radiation. Exposure of 5-S-CD to pyrex-filtered UV light (wavelengths > 320 nm) was found to induce an oxygen-dependent reaction, leading to, besides abundant polymeric materials, the benzothiazine derivatives I and II (two diastereoisomers). Superoxide dismutase exerted a small inhibitory effect on 5-S-CD consumption, whereas other active oxygen scavengers had no effect on. the reaction course. Addition of glutathione as a hydrogen donor completely suppressed the reaction. With UVB light (wavelength range 280-320 nm) photolysis of 5-S-CD proceeded mainly with formation of 3,4-dihydroxy-phenylalanine, arising presumably by photohomolytic cleavage of the S-CH2 bond followed by desulfuration. These results are of interest in relation to the high susceptibility of fair-complexioned individuals to actinic damage and skin cancer.