Abstract Previous studies have indicated that the methylvalerate subunit of bleomycin (BLM) plays an important role in facilitating DNA cleavage by BLM and deglycoBLM. Eleven methylvalerate analogues have been synthesized and incorporated into deglycoBLM congeners by the use of solid-phase synthesis. The effect of the valerate moiety in the deglycoBLM analogues has been studied by comparison with the parent deglycoBLM A 5 ...