2005 Fiscal Year Final Research Report Summary
Development of a gallium ion recovery system using metallothionein polymer gel
| Project/Area Number |
16560686
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biofunction/Bioprocess
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| Research Institution | Kobe College |
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Principal Investigator |
TERASHIMA Masaki Kobe College, Department of Biosphere Sciences, Professor, 人間科学部, 教授 (30172092)
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| Co-Investigator(Kenkyū-buntansha) |
SHIOMI Naofumi Kobe College, Department of Biosphere Sciences, Professor, 人間科学部, 教授 (20299077)
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| Project Period (FY) |
2004 – 2005
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| Keywords | biotechnology / reuse of waste materials / chemical engineering / protein engineering |
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| Research Abstract |
We have found that metallothionein, a protein known to adsorb cadmium ions, also adsorbs a rare metal gallium ion. In this research, we have tried to create metallothionein polymer genes using a mixture of oligonucleotides. Our final goal is to develop a gallium recovery system from waste electronic devices and factories manufacturing electronics with use of metallothionein polymer gels. First, we have expressed metallothionein dimmer proteins in E.coli The purified dimmer proteins were immobilized on the gel. We have found the following results from the adsorption experiments using the metallothionein immobilized gel and the metallothionein dimmer immobilized gel. (1)Metallothionein dimmer adsorbed gallium ions two times as much as the monomer protein. (2)The dimmer protein shows higher adsorption capacity than the monomer when gallium ion concentration was lower than 0.2 mM. (3)Adsorption isotherm of the dimmer was explained by Langmuir-type equation. To improve the efficiency of the adsorption, we have developed other gene constructs using different promoter system and a peptide-tag for purification. During this modification, a tetramer metallothionein gene has been obtained. The sequence of the tetramer gene had been confirmed by DNA sequencing. We have found that tetramer protein was accumulated as inclusion body in E.coli. Size of the tetramer protein was confirmed by Western blot analysis. To develop the effective recover process, we should develop the effective expression system in E.coli, and the proper refolding process.
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