Inactivation of S-adenosyl-L-homocysteine hydrolase by 6'-cyano-5',6'-didehydro-6'-deoxyhomoadenosine and 6'-chloro-6'-cyano-5',6'-didehydro-6'-deoxyhomoadenosine. Antiviral and cytotoxic effects.

6'-Cyano-5',6'-didehydro-6'-deoxyhomoadenosine (E)-1, (Z)-1, and 6'-chloro-6'-cyano-5',6'-didehydro-6'-deoxyhomoadenosine (E)-2 were synthesized and tested as new mechanism-based inhibitors of AdoHcy hydrolase. Nucleoside (E)-1 was identified as a type I inhibitor of the enzyme, whereas inactivation of the enzyme by nucleosides (Z)-1 and (E)-2 was accompanied by the formation of a covalent labeling of AdoHcy hydrolase.