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Identifier

000288868

Title

FTIR Φασματοσκοπική μελέτη των Κυτοχρωμάτων b και c1 της Κυτοχρωμικής Αναγωγάσης από τον οργανισμό Thermus thermophilus

Alternative Title

FTIR Spectroscopic study of Cytochromes b and c1 from the Thermus thermophilus Cytochrome reductase

Author

Αγγελάκη, Μαριαλένα

Thesis advisor

Βαρώτσης, Κωνσταντίνος

Abstract

The aim of the present study is the spectroscopic investigation of cytochromes b and c1 from Thermus thermophilus cytochrome reductase. Cytochrome reductase is an essential component in cellular respiration. As opposed to eleven subunits in the mitochondrial reductase, the bacterial counterpart consists of only three subunits: cytochrome c1 containing a c-type heme, cytochrome b with two b-type hemes, a high potential (b562) and a low potential one (b566) and the Riskie iron-sulfur protein holding the Riskie center. In this work, we have investigated the complexes of reduced cytochromes b and c1 with carbon monoxide and cyanides anion, by FTIR spectroscopy. The iron of heme b562 binds CO forming both monocarbonyl as well as biscarbonyl complexes. However, this is not the case for cytochrome c1. Particularly, the monocarbonyl b562CO complex presents three discrete conformations with relative intensities varying with pH changes. Furthermore, this specie can be photodissociated by a diode laser beam, providing useful information for the protein backbone. Additionally, the detection of the biscarbonyl complex, reported for the first time, yields important implications regarding the ligand binding to hemes. The binding of CN- to the oxidized cytochromes is also investigated. As opposed to the case of CO, cytochrome c1 can form cyanide complexes. Such species are fully consistent with previously reported cyanide complexes with other ferric heme-proteins. They are found to be independent in pH changes and Η2Ο/D2O exchange. Though, in high pH value, a new complex is formed and for the first time, it is assigned to the protonated cytochrome c1 CN-.

Language

Greek

Issue date

2006-03-07

Collection

School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses

Type of Work--Post-graduate theses

Views

195

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