血红蛋白活性中心铁卟啉具有环状共轭结构,类似于叶绿素,可以吸收特定波长光,光会诱导铁卟啉发生氧化还原反应.研究中发现,紫外区波长光照射血红蛋白的氧化还原反应情况优于铁卟啉特征吸收波长(406 nm)光照射情况.无游离色氨酸(Trp)时,266 nm激光激发后高铁血红蛋白(metHb)、脱氧血红蛋白(deoxyHb)、氧合血红蛋白(HbO2)和碳氧血红蛋白(HbCO)均被激发至各自相应的激发态,其Soret带谱峰衰减至基态的时间大致相同;加入游离Trp后,激发态Trp会转移能量到铁卟啉,在直接和间接光能量双重作用叠加下,激发态铁卟啉衰减时间发生变化.metHb、deoxyHb和HbCO衰减时间明显延长,但对HbO2影响相对较小.根据瞬态吸收光谱、动力学曲线和紫外-可见吸收光谱综合分析可知,在加入游离Trp前后,4种形态血红蛋白在被入射光激发后,铁卟啉均反应至具有(或近似具有)一空位的铁六配位平面卟啉结构状态.%With a circular conjugate structure and similar to that of chlorophyll,the iron porphyrin of hemoprotein can absorb specific wavelengths of light to induce its redox reaction and configuration changes.In our research,we found that the photo-induced redox reaction of hemoprotein with ultraviolet lights has more obvious effects than the reaction irradiated by the iron porphyrin characteristic absorption wavelength (406 nm).Irradiated by 266 nm laser,methemoglobin(metHb),deoxyhemoglobin (deoxyHb),oxygenated hemoglobin (HbO2) and carboxyhemoglobin (HbCO) with the absence of free tryptophan (Trp) can be inspired to their corresponding excited states and the decay processes to the ground state indicated with their corresponding Soret band peak have almost the same time.After adding free Trp,the energy of excited state Trp transfers to iron porphyrin.With dual energy superposition of direct light irradiation and indirect energy transfer,the decay time of excited state iron porphyrin varied in different hemoproteins.The significant prolongations of decay time are observed on the photo-irradiated metHb,deoxyHb and HbCO,while slight influences are detected on the photo-irradiated deoxyHb and HbO2.According to transient absorption,kinetics curve and UV-Vis absorption spectra,the ironporphyrin of four forms of hemoglobin could be excited by incident light or by the energy transfer from excited state Trp,then decay to the state of plane porphyrin structure and six-coordinated Fe with one ligand vacancy.
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