학술논문
Ligand substitution reactions of metallothioneins with EDTA and apo-carbonic anhydrase.
Document Type
Article
Author
Source
Proceedings of the National Academy of Sciences of the United States of America; November 1980, Vol. 77 Issue: 11 p6334-6338, 5p
Subject
Language
ISSN
00278424; 10916490
Abstract
The reactions of Zn-, Zn,Cd-, and Cd-thioneins with EDTA and apo-carbonic anhydrase have been studied. The ligand substitution reaction of zinc with EDTA is multiphasic, having both associative and dissociative components in the rate expression. The cadmium sites are about 2 orders of magnitude less reactive. In contrast, apo-carbonic anhydrase abstracts zinc from Zn-thionein and Zn,Cd-thionein in second-order processes that are 2-3 orders of magnitude more rapid than those involving EDTA and approach the rate for unligated Zn2+ with the apo-protein. In comparison with other zinc proteins, Zn-thionein contains unusually reactive metal sites, suggesting that this protein may be a physiological zinc transfer protein, able to donate zinc to zinc-requiring apo macromolecules.