Redox titrations of carbon monoxide dehydrogenase from Clostridium thermoaceticum /
Carbon monoxide dehydrogenate (CODH) from Clostridium thermoaceticum, a species of acetate-forming, thermophilic bacteria, is one of only five known nickel-containing enzymes found in nature. Each subunit of the enzyme's (αβ)₂ quaternary structure contains 2 Ni, 11-13 Fe, and ~14 sulfide ions o...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733668011&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Carbon monoxide dehydrogenate (CODH) from Clostridium thermoaceticum, a species of acetate-forming, thermophilic bacteria, is one of only five known nickel-containing enzymes found in nature. Each subunit of the enzyme's (αβ)₂ quaternary structure contains 2 Ni, 11-13 Fe, and ~14 sulfide ions organized into the so-called A-, B-, and C-clusters. Of particular interest to our work here, the C cluster is believed to be a Fe₄S₄ cube linked to a Ni. The C cluster has three known redox states: C[], C[], and C[]. We have shown that the two-electron process of conversion from C[] to C[] goes through an intermediary step, forming C[]. This state has only been isolated by treating the enzyme with titanium (III) citrate. To better understand the heterogeneity of CODH, we have conducted several stoichiometry and equilibrium situations of the enzyme using one-electron resultants such as CO, methyl viologen and Ti(III) citrate under CO₂ and Ar atmospheres. Fitting of simulated titration data to the observed changes in EPR spectra showed that the best fit occurs when using only the EPR active clusters as the only redox active clusters. No other redox centers were necessary to fit this model precluding any other redox sites in the region examined. We have further shown by EPR spectroscopy that the C[] state can be isolated from the B[] state under specific redox conditions. Our observations of EPR spectra of C[] by itself are the first obtained for CODH from C. thermoaceticum. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xiii, 81 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 77-80). |