914 J. Med. Chem. 1984, 27,914-917 a large number of binding modes of the large substituents is possible, depending on the conformation of the substituents reIative to the site points used to bind them, very few common site points are found to be capable of explaining the data set. In order to explain the low binding energy of the pyrimidines, it is necessary to assume a steric surface that will exclude some of the binding modes, since ...
