DYNAMICS OF HYDROGEN-ATOMS IN SUPEROXIDE-DISMUTASE BY QUASI-ELASTIC NEUTRON-SCATTERING

The low energy dynamics of the enzyme Cu,Zn superoxide dismutase have been investigated by means of quasielastic neutron scattering in the t emperature range 4-320 K. Below 200 K the scattering is purely elastic , while above this temperature a pronounced decrease in the elastic in tensity is observed, together with the onset of a small quasielastic c omponent. This behavior is similar to that previously observed in othe r more flexible globular proteins, and can be attributed to transition s between slightly different conformational substates of the protein t ertiary structure. The presence of only a small quasielastic component , whose intensity is less than or equal to 25% of the total spectrum, is related to the high structural rigidity of this protein.