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 conformational changes with temperature, affecting their catalytic function.
• The relationship between enzyme structural dynamics and temperature-dependent activity requires atomic-level investigation.

Purpose of the Study:

• To investigate how temperature-induced structural changes in a mesophilic enzyme modulate its temperature-dependent activity.
• To correlate atomic-resolution structural data with kinetic measurements across a range of temperatures.
• To understand the implications of temperature-dependent enzyme conformations on reaction kinetics.

Main Methods:

• Multi-temperature X-ray crystallography was employed to capture enzyme structures from -20°C to 40°C.
• Inhibitors mimicking substrate, intermediate, and product states were used to represent key points in the reaction coordinate.
• Kinetic measurements were performed to assess enzyme activity across the same temperature range.

Main Results:

• Increasing temperature led to greater population of catalytically competent conformations for inhibitors, substrates, and active site loops.
• These structural changes were observed even in temperature ranges exhibiting linear Arrhenius/Eyring behavior.
• Analysis demonstrated that linear kinetic behavior can occur when activation energy/enthalpy values are temperature-dependent.

Conclusions:

• Temperature-dependent structural data at atomic resolution is crucial for interpreting enzymatic kinetic data.
• Enzyme structural ensembles dynamically adapt to temperature, influencing catalytic efficiency.
• The study highlights the complex interplay between enzyme structure, dynamics, and temperature-dependent function.