Monoterpene cyclases. Stereoelectronic requirements for substrate binding and ionization

Area of Science:

• Enzymology
• Natural Product Synthesis
• Plant Biochemistry

Background:

• Salvia officinalis enzymes catalyze geranyl pyrophosphate cyclization to monoterpenes.
• Understanding substrate-enzyme interactions is key to elucidating reaction mechanisms.

Purpose of the Study:

• Investigate substrate recognition by monoterpene cyclases.
• Determine the role of substrate structural features in enzyme catalysis.
• Elucidate the mechanism of ionization and product partitioning.

Main Methods:

• Enzyme assays using geranyl pyrophosphate analogs.
• Inhibition studies to probe substrate binding.
• Analysis of reaction products (olefins and alcohols).

Main Results:

• Pyrophosphate ester is crucial for substrate recognition.
• C2-C3 olefin recognized by geometry; C6-C7 olefin by electronic character.
• Optimal substrate alignment and active site water exclusion control product formation.

Conclusions:

• Detailed model of geranyl pyrophosphate binding topology.
• Insights into the stereochemical and electronic determinants of monoterpene cyclase activity.
• Understanding enzyme mechanisms for controlling natural product biosynthesis.