Properties of the Ribose‐Ring‐Opened Adenine Nucleotide, 2,2′[1‐(9‐adenyl)‐1′‐(tri‐,diphosphoryl‐oxymethyl)]‐dihydroxydiethylether in Mitochondrial Adenine‐Nucleotide Translocation

Abstract
(Adenine‐14C) or (γ‐32P)‐labelled 2,2′(1‐(9‐adenyl)‐1′‐(tri‐, diphosphoryl‐oxymethyl)]‐dihydroxydiethylether (rroANP) was obtained from ANP by cleavage of the C‐2′‐C‐3′ bond by sodium periodate oxidation and subsequent borohydride reduction. Binding of rroANP to rat liver mitochondria revealed carrier‐linked (atractyloside‐sensitive) and unspecific (atractyloside‐insensitive) binding but no transfer across the inner mitochondrial membrane. Kinetic data indicate rroANP as a competitive inhibitor for ANP uptake with Ki=9.3 × 10−5M. Experimental rroANP confirmed that an intact adenine base and three anionic charges of the phosphate chain are essential for the recognition between ANP‐carrier and nucleotide but insufficient for the induction of a transmembrane ANP exchange. In addition mobilisation of the carrier‐nucleotide complex requires an intact ribofuranoside ring system.

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