Calabrese L, Polticelli F, Capo C, Musci G
Department of Biochemical Sciences, Università La Sapienza, Rome, Italy.
Free Radic Res Commun. 1991;12-13 Pt 1:305-12. doi: 10.3109/10715769109145799.
The alkaline spectroscopic transition of the copper at the active site of Cu,Zn superoxide dismutase has been reexamined by room temperature EPR, in order to correlate it with the inhibition of the enzyme activity at high pH. The EPR transition is governed by a single prototropic equilibrium, with pK values of 11.3 and 11.1 for ox and shark superoxide dismutase, respectively. This result suggests possible contributions of changes of the copper environment to the higher pK of the activity/pH curve. When Arg141 was chemically modified by phenylglyoxal treatment of the ox protein, a lower pK value (10.8) was obtained, indicating that Arg141 is involved in the observed modifications of the EPR spectra.
为了将其与高pH值下酶活性的抑制相关联，通过室温电子顺磁共振（EPR）对铜锌超氧化物歧化酶活性位点上铜的碱性光谱跃迁进行了重新研究。EPR跃迁由单一质子转移平衡控制，对于牛和鲨鱼超氧化物歧化酶，其pK值分别为11.3和11.1。该结果表明铜环境的变化可能对活性/pH曲线的较高pK值有贡献。当通过苯乙二醛处理牛蛋白对精氨酸141进行化学修饰时，得到了较低的pK值（10.8），这表明精氨酸141参与了观察到的EPR光谱变化。
