bacteriophage sp-15 , which infects bacillus subtilis , contains a highly modified dna in which 62 % of its thymine residues are replaced by 5- ( 4',5'-dihydroxypentyl ) uracil to which is attached a phosphoglucuronate via a phosphodiester linkage to one of the hydroxyl groups of the pentyl side chain .
C0040087
thymine
C0041917
uracil