Dunn, R.V., Reat, V., Finney, J., Ferrand, M., Smith, J.C. & Daniel, R.M. (2000). Enzyme activity and dynamics: xylanase activity in the absence of fast anharmonic dynamics. Biochemical Journal, 346, 355-358.
Permanent Research Commons link: http://hdl.handle.net/10289/4459
The activity and dynamics of a simple, single subunit enzyme, the xylanase from Thermotoga maritima strain Fj SS3B.1 have been measured under similar conditions, from -70 to +10 °C. The internal motions of the enzyme, as evidenced by neutron scattering, undergo a sharp transition within this temperature range; they show no evidence for picosecond-timescale anharmonic behaviour (e.g. local diffusive motions or jumps between alternative conformations) at temperatures below -50 °C, whereas these motions are strongly activated at higher temperatures. The activity follows Arrhenius behaviour over the whole of the temperature range investigated, -70 to +10 °C. The results indicate that a temperature range exists over which the enzyme rate-limiting step is independent of fast anharmonic dynamics.