How do lipases and esterases work: the electrostatic contribution

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• Lipase/esterase activity is influenced by multiple factors, including electrostatic interactions.
• The enzyme's pH activity profile is largely determined by the electrostatic potential distribution on its molecular surface as a function of pH.
• The active cleft's residue composition (polar/hydrophobic) also plays a crucial role.

Purpose of the Study:

• To investigate the contribution of electrostatic interactions to lipase/esterase activity.
• To map the electrostatic potential distribution on the surface of nine lipases/esterases as a function of pH.
• To correlate these potential maps with known pH-activity profiles to understand enzyme function.

Main Methods:

• Computational mapping of electrostatic potential distribution on the molecular surface of nine lipases/esterases at various pH values.
• Comparison of electrostatic potential maps with experimental pH-activity profiles.
• Analysis of residue distribution (polar, non-polar) within the active site cleft.

Main Results:

• A strong correlation was observed between electrostatic potential maps and enzyme pH-activity profiles.
• A negative potential in the active site is correlated with maximum activity towards triglycerides.
• A hypothesis, the 'electrostatic catapult model,' was proposed for product release.
• Potential roles for charged surface regions in stabilizing phospholipid interactions were suggested for phospholipase-active lipases.

Conclusions:

• Electrostatic interactions are a key determinant of lipase/esterase activity and pH dependence.
• The 'electrostatic catapult model' provides a framework for understanding product release mechanisms.
• Surface electrostatics and residue distribution are critical for understanding lipolytic and phospholipolytic activities at an atomic level.