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Related Experiment Videos

Enzyme activity down to -100 degrees C.

J M Bragger1, R V Dunn, R M Daniel

  • 1Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand.

Biochimica Et Biophysica Acta
|July 19, 2000
PubMed
Summary
This summary is machine-generated.

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Enzyme activity was measured at unprecedented low temperatures using cryosolvents. Results show that protein motions ceasing below the dynamic transition are not essential for enzyme function.

Area of Science:

  • Biochemistry
  • Enzymology
  • Protein Dynamics

Background:

  • Enzyme activity is typically studied at moderate temperatures.
  • The effect of extreme cold on enzyme function is largely unknown.
  • Protein dynamic transitions occur at low temperatures, impacting protein structure and function.

Purpose of the Study:

  • To measure enzyme activity at extremely low temperatures.
  • To investigate the role of protein dynamics in enzyme function at sub-zero temperatures.
  • To determine if there is a lower temperature limit for enzyme activity.

Main Methods:

  • Enzyme activity assays for beef liver catalase and calf intestine alkaline phosphatase.
  • Use of cryosolvents (e.g., methanol, ethylene glycol, DMSO, water mixtures) to maintain fluidity at low temperatures.

Related Experiment Videos

  • Analysis of Arrhenius plots to determine activation energies and temperature dependence.

    • Main Results:

    • Enzyme activity was successfully measured down to -97°C for catalase and -100°C for alkaline phosphatase.
    • Arrhenius plots remained linear across the entire temperature range, indicating consistent activity.
    • Cryosolvents increased Arrhenius activation energies, limiting measurements below -100°C.
    • Observed activity below the protein dynamic transition suggests these motions are not critical for catalysis.

    Conclusions:

    • Enzyme activity can persist at temperatures far below the protein dynamic transition.
    • Intrinsic enzyme properties do not appear to impose a lower temperature limit for activity.
    • Solvent fluidity and substrate diffusion may become limiting factors at extremely low temperatures.