Open AccessA further clue to understanding the mobility of mitochondrial yeast cytochrome c
Author(s) -
Barker Paul D.,
Bertini Ivano,
Del Conte Rebecca,
Ferguson Stuart J.,
Hajieva Parvana,
Tomlinson Esther,
Turano Paola,
Viezzoli Maria Silvia
Publication year - 2001
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2001.02369.x
Subject(s) - chemistry , yeast , periplasmic space , heme , redox , cytochrome c , crystallography , myoglobin , biophysics , helix (gastropod) , cytochrome , biochemistry , mitochondrion , escherichia coli , enzyme , biology , organic chemistry , gene , ecology , snail
A new approach was developed to overproduce 15 N‐enriched yeast iso‐1‐cytochrome c in the periplasm of Escherichia coli in order to perform a study of the motions in the ms–µs time scale on the oxidized and reduced forms through rotating frame 15 N relaxation rates and proton/deuterium exchange studies. It is confirmed that the reduced protein is rather rigid whereas the oxidized species is more flexible. The regions of the protein that display increased internal mobility upon oxidation are easily identified by the number of residues experiencing conformational equilibria and by their exchange rates. These data complement the information already available in the literature and provide a comprehensive picture of the mobility in the protein. In particular, oxidation mobilizes the loop containing Met80 and, through specific contacts, affects the mobility of helix 3 and possibly of helix 5, and of a section of protein connecting the heme propionates to helix 2. The relevance of internal motions to molecular recognition and to the early steps of the unfolding process of the oxidized species is also discussed. In agreement with the reported data, subnanosecond mobility is found to be less informative than the ms–µs with respect to redox dependent properties.