SYNTHESIS OF BLEOMYCIN-A(5) OLIGONUCLEOTIDE DERIVATIVES AND SITE-SPECIFIC CLEAVAGE OF THE DNA TARGET

A method for coupling bleomycin A5 to oligonucleotides is proposed. Th e reaction was carried out between an amino group of a spermidine resi due of the Cu(II) complex of bleomycin A5 (Cu(II)Blm-RH) and a 5'-phos phate group of the oligonucleotides d(pCCAAACA) (I), d(pCGTCCTC) (II), d(pT)16 (III), d(pCAAACA) (IV), and d(pGCCAAACA) (V) activated with a mixture of triphenylphosphine and 2,2'-dipyridyl disulfide in the pre sence of 4-(NN-dimethylamino)pyridine 1-oxide. The yields of the produ cts Cu(II)Blm-R-d(pCCAAACA) (Ia), Cu(II)Blm-R-d(pCGTCCTC) (IIa), Cu(II )Blm-R-d(pT)16 (IIIa), Cu(II)Blm-R-d(pCAAACA) (IVa), and Cu(II)Blm-R-d (pGCCAAACA) (Va) were 60-80 %. After removal of the Cu(II) ion from th e bleomycin A5 oligonucleotide derivatives Ia-IIIa, compounds Ib-IIIb were obtained. Compounds Ia, IVa, Va, and Ib-IIIb were further used fo r modification of the target d(pTGTTTGGCGAAGGA) in the presence of Fe( II) ions and 2-mercaptoethanol. Site-specific cleavage of the target b y Blm coupled to complementary oligonucleotides was demonstrated. It w as shown that efficiency and position of cleavage of the complementary reagents la, Ib, IVa, and Va are determined by their oligonucleotide part while the action of the noncomplementary reagents IIb and IIIb wa s similar to that of the free antibiotic.