tailieunhanh - Báo cáo khoa học: High-pressure effects on horse heart metmyoglobin studied by small-angle neutron scattering

Small-angle neutron scattering experiments were performed on horse azidometmyoglobin (MbN3) at pressures up to 300 spectroscopic techniques have shown that a reorganization of the secondary structure and of the active site occur in this pressure range. The present measurements, performedusingvarious concentrations ofMbN3, showthat the compactness of the protein is not altered as the value of its radius of gyration remains constant up to 300 MPa. | Eur. J. Biochem. 269 4731-4737 2002 FEBS 2002 doi High-pressure effects on horse heart metmyoglobin studied by small-angle neutron scattering Camille Loupiac1 Marco Bonetti2 Serge Pin3 and Patrick Calmettes1 1 Laboratoire Leon Brillouin UMR 12 CNRS 2Service de Physique de l Etat Condense and 3Service de Chimie Moleculaire URA 331 CNRS DSM DRECAM CEA de Saclay Gif-sur-Yvette France Small-angle neutron scattering experiments were performed on horse azidometmyoglobin MbN3 at pressures up to 300 MPa. Other spectroscopic techniques have shown that a reorganization of the secondary structure and of the active site occur in this pressure range. The present measurements performed using various concentrations of MbN3 show that the compactness of the protein is not altered as the value of its radius of gyration remains constant up to 300 MPa. The value of the second virial coefficient of the protein solution indicates that the interactions between the molecules are always strongly repulsive even if their magnitude decreases with increasing pressure. Taking advantage of the pressure-induced contrast variation these experiments allow the partial specific volume of MbN3 to be determined as a function of pressure. Its value decreases by between atmospheric pressure and 300 MPa. In this pressure range the isothermal compressibility of hydrated MbN3 is found to be almost constant. Its value is 10-4 MPa-1. Keywords myoglobin pressure SANS partial volume compressibility. The structure of proteins and their solvent interactions can be modified by temperature pH or chemicals. The application of hydrostatic pressure to a protein solution also provides a manner to alter these physical properties 1-4 . The stability of proteins in very different extreme environmental conditions is of great importance for many biotechnological applications notably food processing. Therefore the various states that proteins can adopt under pressure is a matter .