Articolo in rivista, 2014, ENG, 10.1002/prot.24532

Temperature and pressure effects on C112S azurin: Volume, expansivity, and flexibility changes

Cioni P.; Gabellieri E.; Marchal S.; Lange R.

Istituto di Biofisica, Sezione di Pisa, Area della Ricerca, CNR, via G. Moruzzi, 1, 56124 Pisa, Italy; Université Montpellier 2, UMR-S710, F-34095, France; INSERM Unit 710, Place Eugène Bataillon, Montpellier F-34095, France; Ecole Pratique des Hautes Etudes, Paris F-75007, France; INRA, Université Montpellier 2, UMR-1208, Equipe Biochimie et Technologie Alimentaires, Place Eugène Bataillon, Montpellier, F-34095, France; INSERM U1046, CHU Arnaud de Villeneuve, 371 av. Doyen, Giraud, F-34295 Montpellier, France

The pressure-induced unfolding of the mutant C112S azurin from Pseudo aeruginosa was monitored both under steady state and dynamic conditions. The unfolding profiles were obtained by recording the spectral fluorescence emission as well as by phosphorescence intensity measurements evaluated the difference in free energy, Delta G, as a function of pressure and temperature. The dependence of Delta G on temperature showed concave profile at all pressures. studied A positive heat capacity change of about 4.3 kJ mol(-1) deg(-1) fitted all the curves. The volume change of the reaction showed a moderate dependence on temperature when compared with other proteins previously studied. The kinetic activation parameters (Delta V*, Delta H* Delta S*) were obtained from upward and downward pressure-jump experiments and used to characterize the volumetric and energetic properties of the transition state between native and unfolded protein. Our findings suggest that the folding and unfolding reaction paths passed through different transition states. The change in the phosphorescence lifetime with pressure pointed out that pressure-induced unfolding occurred within two steps: the first leading to an increased protein flexibility; presumably caused by water penetration into the protein. Major structural changes of the tryptophan environment occurred in a second step at higher pressures.

Proteins (Online) 82 (9), pp. 1787–1798

Keywords

Pressure unfolding, Pressure-jump, Protein dynamics, Tryptophan fluorescence, Tryptophan phosphorescence

CNR authors

Gabellieri Edi, Cioni Patrizia

CNR institutes

IBF – Istituto di biofisica

ID: 286806

Year: 2014

Type: Articolo in rivista

Creation: 2014-11-11 11:29:37.000

Last update: 2016-03-04 11:33:16.000

External IDs

CNR OAI-PMH: oai:it.cnr:prodotti:286806

DOI: 10.1002/prot.24532

Scopus: 2-s2.0-84906318157

ISI Web of Science (WOS): 000340940300010