The dehydration reaction mechanism of 2-phospho-D-glycerate to form phosphoenolpyruvate in water and protein environments were studied by the density function theory B3LYP method. The optimal structures of reactants, transition states and products were located at the B3LYP/6-31G* level of theory. The reaction barriers were then predicted at the B3LYP/6-311＋＋G(3df,2p) level of theory. The calculation results show that a high reaction barrier (287.7 kJ/mol) exists for the pathway in which no water molecule is involved|whereas the reaction barrier is lowered obviously for the pathway in which a water molecule is involved because of the formation of a six-membered ring transition state structure. The participation of the Mg^2＋ ion can further lower the reaction barrier. Including two Mg^2＋ ions and one water molecule can reduce the reaction barrier to 91.2 kJ/mol, indicating that a water molecule as well as Mg^2＋ ions plays a very important role in the dehydration reaction of 2-phospho-D-glycerate.

Key words: 2-phospho-D-glycerate, phosphoenolpyruvate, reaction barrier