2-amino-4-[[(2S,3S,4R,5R)-5-(6-aminopurin-9-yl)-3,4-dihydroxyoxolan-2-yl]methyl-methylsulfonio]butanoate 2-amino-4-[[(2S,3S,4R,5R)-5-(6-aminopurin-9-yl)-3,4-dihydroxy-tetrahydrofuran-2-yl]methyl-methyl-sulfonio]butanoate 2-amino-4-[[(2S,3S,4R,5R)-5-(6-amino-9-purinyl)-3,4-dihydroxy-2-tetrahydrofuranyl]methyl-methylsulfonio]butanoate 2-amino-4-[[(2S,3S,4R,5R)-5-(6-aminopurin-9-yl)-3,4-dihydroxy-tetrahydrofuran-2-yl]methyl-methyl-sulfonio]butyrate 2-amino-4-[[(2S,3S,4R,5R)-5-(6-aminopurin-9-yl)-3,4-dihydroxy-oxolan-2-yl]methyl-methyl-sulfonio]butanoate