Computational Study of the Degradation of S-Adenosyl Methionine in Water.

The degradation of S-adenosyl methionine (SAM) to homoserine-γ-lactone (HSL) and methyltioadenine (MTA) in water is studied with MD simulations. The AM1 Hamiltonian is used for the quantum part and the flexible AMBER force field for the HO molecules. The MD simulations predict the free energy barrier for the degradation reaction to be between 109 and 112 kJ mol and an overall gain in free energy of -26 kJ mol.