Pterin 1H–3H tautomerism and its possible relevance to the binding of folate to dihydrofolate reductase
Abstract
Ab initio and free energy perturbation calculations show that the 1H:3H tautomer ratio is 1 :6 for pterin in aqueous solution, implying that the 1H tautomer of folate may be responsible for non-productive binding to dihydrofolate reductase.