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| Title | Spectroelectrochemistry of Redox Enzymes |
| Author/s | Andreas Christenson |
| Department/s |
Analytical Chemistry (S/LTH)
|
| Full-text | Available as PDF Available as PDF Available as PDF Available as PDF Available as PDF Available as PDF Available as PDF |
| Defence date | 2006-12-08 |
| Defence time | 13:15 |
| Defence place | Centre for Chemistry and Chemical Enginering, Sölvegatan 39, Lecture Hall B, Lund University, Lund, Sweden. |
| Opponent | Professor William Heineman |
| Publishing year | 2006 |
| Pages | 169 |
| Document type | Dissertation |
| Language | English |
| Publisher | Department of Analytical Chemistry, Lund University, Lund, Sweden. |
| Popular science abstract Swedish |
Det ljus (fotonflöde) som solen sänder ut är grunden för biologiskt liv. Med denna strålning överförs en del av den frigjorda energin från solen till jordens biosfär, där växterna tar upp de energirika fotonerna och omvandlar fotonenergin till kemisk energi. Den kemiska energin lagras sedan som energirika molekyler som transporteras runt i de biologiska systemen för att möjliggöra biologisk aktivitet. I de studier som gjorts inom ramarna för denna avhandling, ingår undersökning av speciella redoxenzym (komplexa protein molekyler) och deras energinivåer. Vid mätning av dessa enzyms redox potentialer visar sig enzymens tendens att vilja oxideras eller reduceras. Potentialerna kan mätas spektroelektrokemiskt och för detta ändamål utvecklades en spektroelektrokemisk cell. Redoxenzym som teofylineoxidas, sulfitoxidas, bilirubinoxidas, laccas och komplex II studerades med hjälp av denna teknik. Då några av dessa enzymer är mycket komplexa studerades också hur elektronerna transporteras inom dessa stora enzym. Intressanta enzyms mekanistiska beteende kunde följas och utvärderas. |
| Abstract English | A low volume and long optical path spectroelectrochemical cell was constructed and tested in a number of applications such as detection of direct electron transfer (DET) between redox enzymes and gold electrodes, determination of the formal potentials of redox centres in proteins and enzymes, as well as mechanistic studies of heterogeneous and intermolecular electron transfer of copper oxidases and succinate:quinine oxidoreductase (Complex II). The existence of DET between enzymes and electrodes was demonstrated for theophylline oxidase, cytochrome P450 cam, laccase, bilirubin oxidase, sulphite oxidase and Complex II. Spectroelectrochemical investigations of the ET between blue multi-copper oxidases and gold electrodes demonstrated that the mechanism of heterogeneous ET of laccases on gold is completely different from that usually observed on carbon electrodes. At carbon electrodes laccases are electronically connected to the conducting electrode through the T1 copper centre. At gold surfaces, by contrast, the electronic connection of the laccase redox centre to the surface is established through the T2 copper centre. Such an ET connection between the gold surface and the T2 copper centre, severely disturbs the oxygen reduction reaction catalysed by laccase. Similar observation was made for two bilirubin oxidases. Spectroelectrochemical studies of Complex II in the gold capillary cell showed that DET for intact Complex II is realised through the heme center with a low redox potential, hemeL. The study of DET reactions in combination with specific ET mediators and inhibitors, suggested that a postulated proximal quinone binding site may indeed exist in the Complex II structure. Our spectroelectrochemical studies indicate that this quinone binding site seems to be closed when both high and low potential heme sites are reduced. |
| Subject |
Chemistry |
| Keywords | Electrochemistry, Elektrokemi, complex II, bilirubin oxidase, laccase, enzyme mechanism, redox potential, electron transfer, spectroelectrochemistry, redox enzymes, Spectroelectrochemical cell |
| ISBN/ISSN/Other |
ISBN: 91-7422-135-3 |
| Supervisor | Tautgirdas Ruzgas |
| Additional info |
Nikitas Bistolas, Andreas Christenson, Tautgirdas Ruzgas, Christiane Jung, Frieder W Scheller and Ulla Wollenberger. 2004. Spectroelectrochemistry of cytochrome P450cam. Biochemical and Biophysical Research Communications, vol 314 pp 810-816. Elsevier
Andreas Christenson, Eva Dock, Lo Gorton and Tautgirdas Ruzgas. 2004. Direct heterogeneous electron transfer of theophylline oxidase. Biosensors & Bioelectronics, vol 20 pp 176-183. Elsevier
Elena Ferapontova, Andreas Christenson, Anja Hellmark and Tautgirdas Ruzgas. 2004. Spectroelectrochemical study of heme- and molybdopterin cofactor-containing chicken liver sulphite oxidase. Bioelectrochemistry, vol 63 pp 49-53. Elsevier
Sergey Shleev, Andreas Christenson, Vladimir Serezhenkov, Dosymzhan Burbaev, Alexander Yaropolov, Lo Gorton and Tautgirdas Ruzgas. 2005. Electrochemical redox transformations of T1 and T2 copper sites in native Trametes hirsuta laccase at gold electrode. Biochemical Journal, vol 385 pp 745-754. Portland Press
Sergey Shleev, Oxana Nikitina, Andreas Christenson, Curt T. Reimann, Alexander Yaropolov, Tautgirdas Ruzgas and Lo Gorton. 2006. Characterization of two new multiforms of Trametes pubescens laccase. Bioorganic Chemistry, Elsevier (inpress)
Andreas Christenson, Sergey Shleev, Nicolas Mano, Adam Heller and Lo Gorton. 2006. Redox potentials of the blue copper sites of bilirubin oxidases. BBA (Bioenergetics), Elsevier (inpress)
Andreas Christenson, Tobias Gustavsson, Tautgirdas Ruzgas, Lo Gorton and Cecilia Hägerhäll. 2006. Direct and mediated electron transfer between intact succinate:quinone oxidoreductase from Bacillus subtilis and a surface modified gold electrode reveals redox state dependent conformational changes. (manuscript)
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