Electrochemical study of human foetal liver metallothionein: influence of the additions of cadmium and zinc

Three different isoforms of human foetal liver metallothionein (HFL MT), MT -0, MT-1 and MT-2, have been characterised using electrochemical methods su ch as differential pulse polarography (DPP) and square wave voltammetry (SW V) at the mercury electrode. MT-0 and MT-2 contain mostly zinc, whilst MT-I contains cadmium and zinc. Therefore, MT-0 and MT-2 behave in a similar ma nner, but MT-1 behaves differently. These human MTs are not very stable com pounds. Studies on additions of cadmium and zinc to them have been carried out. MTs are able to incorporate these added metal ions into their molecula r structure, provoking a change in the complexing forms of both cations. In fact, two different polarographic responses due to the reduction of comple xed Cd(II), and three responses from the reduction of the complexed Zn(II) have been distinguished. These species are, however, inter-related. The cha nge in pH in a very narrow range, from 8 to 9, provokes important changes i n the features of the polarogram and hence in the detection of the differen t species. (C) 2000 Elsevier Science B.V. All rights reserved.