A structural perspective on the temperature-dependent activity of enzymes

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• Enzyme activity is temperature-dependent, but the structural basis for this modulation is not fully understood.
• Unlike small molecules, enzymes exhibit significant temperature-dependent structural variations.
• The relationship between enzyme structure and temperature-dependent kinetics requires further investigation.

Purpose of the Study:

• To investigate the atomic-resolution structural changes in a mesophilic enzyme across a temperature range (-20°C to 40°C).
• To correlate these structural dynamics with enzyme activity and kinetic parameters.
• To understand how temperature-induced structural shifts influence catalytic competence.

Main Methods:

• Multi-temperature X-ray crystallography was employed.
• Inhibitors mimicking substrate, intermediate, and product states were used.
• Structural data were collected from -20°C to 40°C for a mesophilic enzyme.

Main Results:

• Increasing temperature led to greater population of catalytically competent conformations for inhibitors, substrates, and loop motifs.
• These structural changes occurred even in temperature ranges exhibiting linear Arrhenius/Eyring behavior.
• Derived thermodynamic parameters may differ significantly from those obtained through standard Arrhenius/Eyring fits.

Conclusions:

• Temperature-dependent structural data are crucial for interpreting enzymatic kinetic data.
• Enzyme structural ensembles dynamically adapt to temperature, impacting catalytic activity.
• Linear kinetic behavior does not preclude underlying temperature-dependent structural changes.