Arsenic transfer between metallothionein proteins at physiological pH.
As³+ bound to the two-domain, recombinant human metallothionein (isoform 1a) is stable at pH 7 and translocates via protein-protein interactions to other metallothionein proteins. The data show As³+ transfer from the two-domain β-α-hMT to binding sites in the isolated apo-β-hMT and apo-α-hMT. Under conditions of equilibrium, apo- and partially-metallated species coexist indicating that noncooperative demetallation of the As(6)-βα-hMT occurrs. As³+ transfer under conditions (pH 7) where the free As³+ ion is not stable, provides evidence that Cd²+ and Zn²+ transfer may also take place through protein-protein interactions and that partially metallated Cd-MT and Zn-MT would be stable.
Ngu
Thanh T
TT
Department of Chemistry, The University of Western Ontario, London, Ontario N6A5B7, Canada.
Dryden
Michael D M
MD
Stillman
Martin J
MJ
D001151:Arsenic / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism; D004795:Enzyme Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D015032:Zinc / Q000378:metabolism
D011994:Recombinant Proteins; C407523:metallothionein isoform 1; D002104:Cadmium; D008668:Metallothionein; D015032:Zinc; D001151:Arsenic