Ligand substitution reactions of metallothioneins with EDTA and apo-carbonic anhydrase.
AUTOR(ES)
Li, T Y
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=350278Documentos Relacionados
- Mitochondrial carbonic anhydrase.
- Nucleotide sequence of pea cDNA encoding chloroplast carbonic anhydrase.
- X-ray absorption studies of halide binding to carbonic anhydrase.
- Studies in Plant Carbonic Anhydrase. II. Kinetic Studies1
- Nucleotide sequence of a cDNA encoding rice chloroplastic carbonic anhydrase.
