Biosynthesis of the Nucleoside Antibiotics

About seventy naturally occurring nucleoside analogs have been isolated to date. As with the numerous other analog types that have been isolated from microorganisms, these nucleoside analogs have also been useful biochemical probes in the elucidation of the complex steps of RNA, DNA, protein, and cell wall synthesis as well as cytoplasmic, mitochondrial, and nuclear processes. The structures of the nucleoside analogs can be classified into five groups. One group is structurally similar to the purine nucleosides or nucleotides; a second group is structurally similar to the pyrimidine nucleosides; a third group is the pyridine nucleosides; a fourth group is the diazepine nucleosides; and the fifth group is the maleimide nucleosides