A conformational basis for the antiviral inactivity of tetrazole ribonucleosides.

The antiviral activity of ribavirin has been associated with its inhibition of the enzyme, IMP dehydrogenase. The ability of ribavirin to inhibit this enzyme has previously been shown to be related to its stability in the high anti glycosidic conformation. The antiviral effectiveness of several analogs of ribavirin have been investigated recently. The evidence indicates their antiviral effectiveness is related to their stability in the high anti conformation. Recently the disposition of purine analogs that pass through the inosine monophosphate branch point has been investigated. The results of these studies are consistent with the concept that the conversion of IMP to XMP requires the high anti conformation and that the conversion of IMP to adenylosuccinate requires some other conformation, possibly the anti conformation.