Abstract The conformationally restricted adenine nucleotide analogs 8,3′anhydro-8-oxy-9-(β-ᴅ-xylofurano-syl) adenine-5′-O-tri (di) -phosphate (I) , and 8,2′-anhydro-8-oxy-9-(β-ᴅ-arabinofuranosyl) adenine-5′-O-tri (di)-phosphate (II), were prepared chemically as their α-32P-labelled compounds and compared with syn-structured 8-bromo AT(D) P in mitochondrial adenine nucleotide translocation. The experimental findings demonstrate that the heterocycle-ribose orientation affects the carrier mediated adenine nucleotide transport very strongly, i. e. a non fixed adenine heterocycle in the anti region is prerequisite for the bound nucleotide to induce the transfer action of the adenine nucleotide carrier.