Electrochemical and infrared spectroscopic analysis of the interaction of the CuA domain and cytochrome c552 from Thermus thermophilus

Abstract The hydrophobically guided complex formation between the Cu A fragment from Thermus thermophilus ba 3 terminal oxidase and its electron transfer substrate, cytochrome c 552 , was investigated electrochemically. In the presence of the purified Cu A fragment, a clear downshift of the c 552 redox potential from 171 to 111 mV ± 10 mV vs SHE′ was found. Interestingly, this potential change fully matches complex formation with this electron acceptor site in other oxidases guided by electrostatic or covalent interactions. Redox induced FTIR difference spectra revealed conformational changes associated with complex formation and indicated the involvement of heme propionates. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).