Theoretical Studies On The Dehydration Reaction Mechanism Of 2-phospho-d-glycerate

Theoretical studies on the dehydration reaction mechanism of 2-phospho-D-glycerate to form phosphoenolpyruvate were carried out using density function theory B3LYP methods. The optimal structures of reactants, transition states and products were located at the B3LYP/6-31G* level of theory, and the reaction barriers were therefore predicted at the B3LYP/6-311++G(3df,2p) level of theory. The calculation results show that:(1) a high reaction barrier (287.7kJ/mol) exists for the pathway in which no water molecule involves; whereas for the pathways in which a water molecule involves the reaction barriers are lowered obviously because of the formation of a six-membered ring transition state structure. The participation of the Mg²⁺ ion can further lower the reaction barrier. Including two Mg²⁺ ions and one water molecule can reduce the reaction barrier to 91.2 kJ/mol, indicating that water molecule as well as Mg²⁺ ions plays a very important role in the dehydration reaction of 2-phospho-D-glycerate.(2) around Mg²⁺ ions there are water molecules regard them as ligands assist this reaction, when there is only one Mg²⁺ ion and no water molecule involves, can achieve through a four-membered ring transition state structure, and when a water molecule involves, can achieve through a six-membered ring transition state structure, both them reaction barrier are very high reaction barrier and can not reaction at normal temperature. when there are two Mg²⁺ ions and no water molecule involves, can achieve through a four-membered ring transition state structure and reaction barrier not enough to 101.1kJ/mol, and when a water molecule involves, can achieve through a six-membered ring transition state structure and reaction is 118.2 kJ/mol, both them can occur at normal temperature. Therefore around Mg²⁺ ions there are water molecules regard them as ligands assist this reaction, two Mg²⁺ ions together function can make this reaction achieve.