Udom A O, Brady F O
Biochem J. 1980 May 1;187(2):329-35. doi: 10.1042/bj1870329.
The ability of rat liver zinc-thionein to donate its metal to the apo-enzymes of the zinc enzymes horse liver alcohol dehydrogenase, yeast aldolase, thermolysin, Escherichia coli alkaline phosphatase and bovine erythrocyte carbonic anhydrase was investigated. Zinc-thionein was as good as, or better than, ZnSO(4), Zn(CH(3)CO(2))(2) or Zn(NO(3))(2) in donating its zinc to these apo-enzymes. Apo-(alcohol dehydrogenase) could not be reactivated by zinc salts or by zinc-thionein. Incubation of the other apo-enzymes with near-saturating amounts of zinc as ZnSO(4), Zn(CH(3)CO(2))(2), Zn(NO(3))(2), or zinc-thionein resulted in reactivation of the apo-enzymes. With apo-aldolase zinc-thionein gave 100% reactivation within 30min. Reactivation by ZnSO(4) and Zn(CH(3)CO(2))(2) was complete and instantaneous. Zinc-thionein was somewhat better than Zn(NO(3))(2) in completely reactivating apo-thermolysin. With apo-(alkaline phosphatase) 43% reactivation was obtained with Zn(CH(3)CO(2))(2) and 18% with zinc-thionein. With apo-(carbonic anhydrase) zinc-thionein was better than ZnSO(4), Zn(CH(3)CO(2))(2) or Zn(NO(3))(2), with a maximal reactivation of 54%. That zinc was really being transferred from zinc-thionein to apo-(carbonic anhydrase) was shown by the fact that 2,6-pyridine dicarboxylic acid and 1,10-phenanthroline had minimal effects on the reactivation of apo-(carbonic anhydrase) when added after the incubation {[apo-(carbonic anhydrase)+zinc thionein]+chelator}, but inhibited reactivation when added before the incubation {apo-(carbonic anhydrase)+[zinc-thionein+chelator]}. These observations support the idea that zinc-thionein can function in zinc homeostasis as a reservoir of zinc, releasing the metal to zinc-requiring metalloenzymes according to need.
研究了大鼠肝脏锌硫蛋白将其金属转移至锌酶马肝醇脱氢酶、酵母醛缩酶、嗜热菌蛋白酶、大肠杆菌碱性磷酸酶和牛红细胞碳酸酐酶的脱辅基酶的能力。在将其锌转移至这些脱辅基酶方面，锌硫蛋白与硫酸锌、醋酸锌或硝酸锌表现相当或更优。脱辅基（醇脱氢酶）不能被锌盐或锌硫蛋白重新激活。将其他脱辅基酶与接近饱和量的以硫酸锌、醋酸锌、硝酸锌形式存在的锌或锌硫蛋白一起孵育，会导致脱辅基酶重新激活。对于脱辅基醛缩酶，锌硫蛋白在30分钟内使其100%重新激活。硫酸锌和醋酸锌的重新激活是完全且即时的。在完全重新激活脱辅基嗜热菌蛋白酶方面，锌硫蛋白比硝酸锌稍好。对于脱辅基（碱性磷酸酶），醋酸锌使其43%重新激活，锌硫蛋白使其18%重新激活。对于脱辅基（碳酸酐酶），锌硫蛋白比硫酸锌、醋酸锌或硝酸锌更优，最大重新激活率为54%。2,6 - 吡啶二甲酸和1,10 - 菲咯啉在孵育后添加{[脱辅基（碳酸酐酶）+锌硫蛋白]+螯合剂}时，对脱辅基（碳酸酐酶）的重新激活影响最小，但在孵育前添加{脱辅基（碳酸酐酶）+[锌硫蛋白+螯合剂]}时会抑制重新激活，这一事实表明锌确实从锌硫蛋白转移至脱辅基（碳酸酐酶）。这些观察结果支持了锌硫蛋白可作为锌的储存库在锌稳态中发挥作用，根据需要将金属释放给需要锌的金属酶的观点。
