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研究了水-乙腈混合溶液中SO~●_4-自由基氧化酪氨酸的反应.实验结果表明,SO~●_4-自由基氧化酪氨酸的反应机制不因乙腈的加入而改变,但所产生的瞬态粒子的动力学行为受到较大影响.随介质中乙腈体积分数的增加,SO~●_4-的衰变速率减慢而酪氨酸中性自由基(TyrO●)的衰变速率加快.我们认为这两种自由基所呈现出来的相反的溶剂效应是由于其所带电荷的不同.随介质中乙腈体积分数的增加,SO~●_4-氧化酪氨酸的反应速率减慢.这一实验结果意味着,在有机溶剂存在的情况下TyrO●/TyrOH的氧化还原电势可能发生了变化,从而旁证了关于TyrO●/TyrOH的氧化还原电势因酪氨酸从游离状态变到肽或蛋白质中而发生变化的推测.
The reaction of SO_2O_4-free radical tyrosine was studied in water-acetonitrile mixed solution.The experimental results show that the reaction mechanism of SO___4-free radical tyrosine oxidation does not change due to the addition of acetonitrile, The dynamic behavior of the transient particles is greatly affected.With the increase of acetonitrile volume fraction in the medium, the decay rate of SO_4_4- is slowed down and the decay rate of tyrosine free radical (TyrO_) is accelerated. We think that the opposite solvent effect exhibited by these two free radicals is due to the difference in the charges they carry. The reaction rate of SO_4-oxotyrosine slowed down as the volume fraction of acetonitrile in the medium increased The experimental results imply that the redox potential of TyrO * / TyrOH may change in the presence of an organic solvent, thus confirming that the redox potential for TyrO * / TyrOH changes from a free state to a peptide or protein The changes have been speculated.