REACTIVATION INVITRO OF ZINC-REQUIRING APO-ENZYMES BY RAT-LIVER ZINC-THIONEIN
REACTIVATION INVITRO OF ZINC-REQUIRING APO-ENZYMES BY RAT-LIVER ZINC-THIONEIN
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DOI：
10.1042/bj1870329
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发表时间：
1980-01-01
影响因子：
4.1
通讯作者：
BRADY, FO
中科院分区：
文献类型：
--
作者：
UDOM, AO;BRADY, FO
The ability of rat liver Zn-thionein to donate its metal to the apo-enzymes of the Zn 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 ZnSO4, Zn(CH3CO2)2 or Zn(NO3)2 in donating its Zn to these apo-enzymes. Apo-(alcohol dehydrogenase) could not be reactivated by Zn salts or zinc-thionein. Incubation of the other apo-enzymes with near-saturating amounts of Zn as ZnSO4, Zn(CH3CO2)2, Zn(NO3)2 or zinc-thionein resulted in reactivation of the apo-enzymes. With apo-aldolase zinc-thionein gave 100% reactivation within 30 min. Reactivation by ZnSO4 and Zn(CH3CO2)2 was complete and instantaneous. Zinc-thionein was somewhat better than Zn(NO3)2 in completely reactivating apo-thermolysin. With apo-(alkaline phosphatase) 43% reactivation was obtained with Zn(CH3CO2)2 and 18% with zinc-thionein. With apo-(carbonic anhydrase) zinc-thionein was better than ZnSO4, Zn(CH3CO2)2 or Zn(NO3)2, with a maximal reactivation of 54%. Zn was being transferred from zinc-thionein to apo-(carbonic anhydrase), as 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]}. Zinc-thionein can apparently function in Zn homeostasis as a reservoir of Zn, releasing the metal to Zn-requiring metalloenzymes according to need.
