Butorina D N, Krasnovskiĭ A A, Priezzhev A V
Bakh Institute of Biochemistry, Russian Academy of Sciences, Lomonosov Moscow State University, Vorob'evy Gory, Moscow, Russia.
Biofizika. 2003 Mar-Apr;48(2):201-9.
The kinetic parameters of porphyrin-photosensitized formation and deactivation of singlet molecular oxygen (1O2) and their dependence on the concentration of the 1O2 quencher sodium azide were investigated in air-saturated water, ethanol, and aqueous micellar solutions of detergents using time-resolved measurements of oxygen phosphorescence under pulsed laser excitation. The lifetimes of 1O2 formation and deactivation and the rate constants of 1O2 quenching by sodium azide were determined. It was shown that, with no azide in the solutions, the rise in phosphorescence intensity after the laser flash corresponded to the kinetics of energy transfer from the porphyrin triplet molecules to oxygen, while the decay kinetics corresponded to the kinetics of 1O2 deactivation. In the presence of detergent, a considerable increase in the 1O2 lifetime was observed, which is likely due to the localization of 1O2 molecules mostly in lipophilic micelles and not in the water phase. If relatively high azide concentrations were used, the lifetime of the porphyrin triplet state did not change but the 1O2 lifetime decreased to values similar to those in living cells. In this case, the inversion of the phosphorescence kinetic phases was observed. The rise corresponded to 1O2 deactivation, and the decay, to the energy transfer from triplet porphyrin to oxygen. The data suggest that, in living cells, 1O2 molecules are also located mainly in lipophilic structures and the 1O2 lifetime determines the kinetics of the phosphorescence rise after the laser pulse.
在空气饱和的水、乙醇以及洗涤剂的胶束水溶液中，利用脉冲激光激发下的氧磷光时间分辨测量，研究了卟啉光敏化形成和猝灭单线态分子氧（¹O₂）的动力学参数及其对¹O₂猝灭剂叠氮化钠浓度的依赖性。测定了¹O₂形成和猝灭的寿命以及叠氮化钠猝灭¹O₂的速率常数。结果表明，溶液中不存在叠氮化钠时，激光闪光后磷光强度的上升对应于从卟啉三重态分子到氧的能量转移动力学，而衰减动力学对应于¹O₂的猝灭动力学。在存在洗涤剂的情况下，观察到¹O₂寿命显著增加，这可能是由于¹O₂分子主要定位于亲脂性胶束而非水相。如果使用相对较高浓度的叠氮化钠，卟啉三重态的寿命不变，但¹O₂寿命降至与活细胞中相似的值。在这种情况下，观察到磷光动力学相的反转。上升对应于¹O₂的猝灭，而衰减对应于从三重态卟啉到氧的能量转移。数据表明，在活细胞中，¹O₂分子也主要位于亲脂性结构中，并且¹O₂寿命决定了激光脉冲后磷光上升的动力学。
