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1. a part or organ having the same function as another, but of different evolutionary origin.
2. a chemical compound having a structure similar to that of another but differing from it in respect to a certain component; it may have similar or opposite action metabolically. Also spelled analog.
nucleoside analogue a structural analogue of a nucleoside, a category that includes both purine analogues and pyrimidine analogues.
purine analogue a structural analogue of one of the purine bases(purine, adenine, or guanine); mercaptopurine and thioguanine are used as antineoplastics and azathioprine is an immunosuppressive. The antiviral agent vidarabine is an analogue of the adenine nucleoside adenosine.