Secm-spr Combination Technology Of Sulfur Protein And Metal Ion Interaction

Metallothioneins are a class of metalloproteins that play an important role in essential metal regulation and heavy metal detoxification.The activity of metal ion sequestration,release,and transfer by MTs are dynamic cellular processes.Detecting the structure changes during the dynamic processes is of immense biological importance for unraveling the protein structure/function relationship. However,many traditional techniques monitoring changes either in solution or in the solid state are not amenable for studies of rapid functional and dynamic changes of proteins at the solid/liquid interface. Furthermore,there are certain inherent limitations.We describe herein the real-time SECM-SPR detection of interaction between copper ion and surface-confined MT.It is shown that not only did the couple technique enable us to control the extent of metal binding,but also allowed the binding stoichiometry and dynamics to be quantitatively determined.It reveals that copper ion sequestration by apo-MT and copper ion release by MT are both stepwise processes, leading to three stable structures containing different numbers of metal ions,which are Cu₅-MT,Cu₉-MT,Cu₁₂-MT,respectively.Since MTs in their native structure generally do not exhibit well-defined voltammograms at solid electrodes,our work expands the application of SECM-SPR from studies of redox proteins to proteins that do not undergo facile electron transfer reactions.After this,the research approach is applied to detect the process of mercury sequestration by apo-MT.It shows that MT reaches the satuation state,when the molar ratio of Hg²⁺/MT is up to 18.When the ratio is beyond 120,the structures/compositions of MT turn out to be destroyed.