铂化金属硫蛋白与羟自由基反应速率常数的测定

Interactions of hydroxyl radicals with Pt 7 thionein

目的：测量铂化金属硫蛋白（Ｐｔ７Ｔｈ）与羟自由基（ＯＨ·）的反应速率常数。方法：脉冲辐解Ｎ２Ｏ饱和的Ｐｔ７Ｔｈ及其ＫＳＣＮ竞争体系的水溶液。结果：Ｐｔ７Ｔｈ中的巯基（ＲＳ－）与羟自由基（ＯＨ·）反应生成巯基自由基（ＲＳ·）的反应速率常数为１．６×１０１１Ｌ·ｍｏｌ－１·ｓ－１，ＲＳ与ＲＳ·生成阴离子自由基ＲＳＳＲ·－的正反应速率常数为８．２×１０９Ｌ·ｍｏｌ－１·ｓ－１，逆反应速率常数为１．２×１０５ｓ－１。结论：Ｐｔ７Ｔｈ具有较强的清除ＯＨ·的能力，对含铂抗癌药物的临床应用具有重要意义。

OBJECTIVE:To determine the rate constants of the reaction of Pt 7 thionein (Pt 7Th) with hydroxyl radicals.METHODS:Pulse radiolytic study was used by employing the N 2O saturated aqueous Pt 7Th solution competing against KSCN.RESULTS:The hydroxyl radicals OH · efficiently reacted with Pt 7Th by forming a thiyl radical RS · with a second order constant of 1.6×10 11 L·mol -1 ·s -1 ,and the thiyl radical RS · reacted rapidly and reversibly with a thiolate in the Pt 7Th to form radical anion RSSR ·- with a constant of 8.2×10 8 L·mol -1 ·s -1 per thiolate,while the constant of the decay of this radical anion was 1.2×10 5s -1 .CONCLUSION:Pt 7Th has a special feature to protect cells against OH · radiolysis.