Affinity receptor site models

TABLE III. ANTAGONIST POTENCY AND BINDING AFFINITY OF BENZOMORPHANS WITH VARYING N-SUBSTITUENTS AND THEIR ENERGIES OF INTERACTION WITH MODEL ANIONIC RECEPTOR SITES. ... 

With the exception of the cyclopropylmetbane, the main discrepancy is the relatively large energy calculated for the 2,3 - dimethylfuran. The stabilization energies of the AMS complexes calculated by the empirical method correlate more with the measured affinities and antagonist potencies than those for the AMP complexes. Additionally, more stable complexes with AMS are found by the empirical method than by the PCILO method. Taken together, the results of both methods indicate that either the phosphate or sulfate anion is a reasonable model for the anionic opiate receptor site. 

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