Sionkowska Alina
Faculty of Chemistry, N. Copernicus University, Gagarin 7, 87-100 Torun, Poland.
J Photochem Photobiol B. 2006 Jul 3;84(1):38-45. doi: 10.1016/j.jphotobiol.2006.01.007. Epub 2006 Feb 28.
An investigation of the photochemical properties of collagen Type I in acetic acid solution was carried out using nanosecond laser irradiation. The transient spectra of collagen solution excited at 266 nm show two bands. One of them with maximum at 295 nm and the second one with maximum at 400 nm. The peak at 400 nm is assigned to tyrosyl radicals. The first peak of the transient absorption spectra at 295 nm is probably due to photoionisation producing collagen radical cation. The transient for collagen solution in acetic acid at 640 nm was not observed. It is evidence that there is no hydrated electron in the irradiated collagen solution. The reactions of hydrated electrons and ()OH radicals with collagen have been studied by pulse radiolysis. In the absorption spectra of products resulting from the reaction of collagen with e(aq)(-) no characteristic maximum absorption in UV and visible light region has been observed. In the absorption spectra of products resulting from the reaction of the hydroxyl radicals with collagen two bands have been observed. The first one at 320 nm and the second one at 405 nm. Reaction of ()OH radicals with tyrosine residues in collagen chains gives rise to Tyr phenoxyl radicals (absorption at 400 nm).
利用纳秒激光辐照对乙酸溶液中I型胶原蛋白的光化学性质进行了研究。在266 nm激发的胶原蛋白溶液的瞬态光谱显示出两个谱带。其中一个在295 nm处有最大值,另一个在400 nm处有最大值。400 nm处的峰归属于酪氨酸自由基。瞬态吸收光谱在295 nm处的第一个峰可能是由于光离子化产生了胶原蛋白自由基阳离子。未观察到乙酸中胶原蛋白溶液在640 nm处的瞬态。这证明在辐照的胶原蛋白溶液中不存在水合电子。通过脉冲辐解研究了水合电子和()OH自由基与胶原蛋白的反应。在胶原蛋白与e(aq)(-)反应产生的产物的吸收光谱中,未观察到紫外和可见光区域的特征最大吸收。在羟基自由基与胶原蛋白反应产生的产物的吸收光谱中,观察到两个谱带。第一个在320 nm处,第二个在405 nm处。()OH自由基与胶原蛋白链中的酪氨酸残基反应产生酪氨酸苯氧基自由基(在400 nm处有吸收)。