the beginning, medicinal therapy consisteodf concoctions coadministered
with incantations. Little thought was given to dissecting out the
contributions of the pharmacology of the concoction from the spiritual
consequences of the incantations. Eventually, potions and extracts were
recognized to have predictable activity that could be observed and described
objectively. Then came the capacity to estimate potency,t o l eading
concentration and purification.
Here we examine the enantioselectivity of the allosteric and substrate bind-ing sites of murine ribonucleotide reductase (mRR). l-ADP binds to the
active site andl-ATP binds to both the s- and a-allosteric sites of mR1
with affinities that are only three- to 10-fold weaker than the values for the
corresponding d-enantiomers. These results demonstrate the potential of
l-nucleotides for interacting with and modulating the activity of mRR, a
cancer chemotherapeutic and antiviral target.