Cu+ distribution in metallothionein fragments.
The differential distribution of Cu+ between separate alpha and beta domains of metallothionein (the isolated peptide fragments) and the rate of transfer of Cu+ between the two domains using copper-thiolate specific emission spectroscopy are reported. Kinetic data show the rate of transfer of Cu+ from the Cu6alpha to the Cd3beta domain is 2 x 10(-1) s(-1) while the transfer from Cu6beta to the Cd4alpha domain is much slower at 8 x 10(-3) s(-1), indicating the greater binding affinity of Cu+ for the MT beta domain. We report that the emission intensity of Cu6beta is 0.45 the emission intensity of Cu6alpha-MT. Lambda(max) is shown to be a probe of the environment of the Cu+. A series of copper-containing domain intermediates to the formation of the filled Cu6S9-beta and Cu6S11-alpha-clusters are identified. A mechanism is proposed for the formation of Cu12(betaalpha)-MT that involves metal exchange reactions of Cu+ ions from the alpha to the beta domain with initial formation of a Cu4beta-cluster.
Salgado
Maria T
MT
Department of Chemistry, University of Western Ontario, London, Ont., Canada N6A 5B7.
Stillman
Martin J
MJ
D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008956:Models, Chemical; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013057:Spectrum Analysis / Q000379:methods
D010446:Peptide Fragments; D011994:Recombinant Proteins; D003300:Copper; D008668:Metallothionein