Glucose isomerization to fructose from ab initio molecular dynamics simulations

Area of Science:

• Biochemistry
• Physical Chemistry
• Computational Chemistry

Background:

• Glucose isomerization to fructose is a key reaction in carbohydrate chemistry.
• Understanding the reaction mechanism is crucial for various industrial and biological processes.

Purpose of the Study:

• To elucidate the detailed mechanism of glucose isomerization to fructose in acidic aqueous solution.
• To determine the energy barriers for key steps in the isomerization process using advanced computational methods.

Main Methods:

• Car-Parrinello molecular dynamics (CPMD) simulations.
• Metadynamics (MTD) simulations to overcome energy barriers.
• Investigation of reaction pathways and transition states.

Main Results:

• The isomerization initiates with protonation of the C2-OH group, forming a furanose aldehyde intermediate.
• A hydride transfer from C2 to C1, followed by C2 carbocation formation, is a critical step.
• The energy barrier for hydride transfer is approximately 35 kcal/mol.
• The final rehydration of the C2 carbocation has an estimated barrier of 25 kcal/mol.

Conclusions:

• CPMD-MTD simulations provide a detailed mechanistic insight into glucose-fructose isomerization.
• The identified energy barriers highlight the rate-limiting steps of the reaction.
• Computational simulations are valuable tools for understanding complex chemical transformations.