Denaturation of a halophilic enzyme monitored by small-angle neutron scattering.
Malate dehydrogenase from Halobacterium maris mortui exists in 4 M-NaCl as a stable protein dimer, with which are associated unusually large amounts of salt and water. In 1 M-NaCl at 25 degrees C, it denatures with a time-constant of about 0.5 h-1. Small-angle neutron scattering data from the protein under these conditions were monitored regularly over more than 12 hours during denaturation. They are quantitatively consistent with a model in which the protein dimer loses its exceptional salt and water-binding properties, and dissociates into monomers that partially unfold and have the interactions with solvent expected from their relatively charged amino acid composition. The exceptional salt and water-binding by the native enzyme, therefore, is associated with the native structure of the dimer.
D006217:Halobacterium / Q000201:enzymology*; D008291:Malate Dehydrogenase; D009502:Neutrons; D011489:Protein Denaturation; D012542:Scattering, Radiation
D008291:Malate Dehydrogenase