Biochemical Journal 1988-07-15

The role of the gulose-mannose part of bleomycin in activation of iron-molecular oxygen complexes.

A Kénani, C Bailly, N Helbecque, J P Catteau, R Houssin, J L Bernier, J P Hénichart

Index: Biochem. J. 253(2) , 497-504, (1988)

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Abstract

A comparison of the complexing properties of metal ions and O2 activation by bleomycin-A2 (BLM-A2) and deglyco-BLM-A2 is presented. Deglyco-BLM-A2 is obtained from the parent derivative by HF cleavage of the sugar moiety followed by h.p.l.c. purification. Complexing of Cu(II) and Fe(III) is studied by using c.d. and e.s.r. spectroscopy. Spin-trapping experiments in the presence of phenyl N-t-butylnitrone indicated lower production of free radicals by deglyco-BLM-A2. Finally, a proposal is made to explain this discrepancy, focusing on the probable role of the gulose-mannose moiety acting as a protecting pocket, comparable with the pocket and picket-fence porphyrins described for haemoproteins.