Enzyme activity and dynamics: xylanase activity in the absence of fast anharmonic dynamics.
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 degrees 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 degrees 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 degrees C. The results indicate that a temperature range exists over which the enzyme rate-limiting step is independent of fast anharmonic dynamics.
Dunn
R V
RV
Department of Biological Sciences, University of Waikato, Hamilton, New Zealand.
Réat
V
V
Finney
J
J
Ferrand
M
M
Smith
J C
JC
Daniel
R M
RM
D004789:Enzyme Activation; D004926:Escherichia coli; D013696:Temperature; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000737:chemistry* / Q000378:metabolism
D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase