DNA containing a chemically reduced apurinic site is a high affinity ligand for the E. coli formamidopyrimidine-DNA glycosylase.

摘要: The E. coli Formamidopyrimidine-DNA Glycosylase (FPG protein), a monomeric DNA repair enzyme of 30.2 kDa, was purified to homogeneity in large quantities. FPG protein excises imidazole ring-opened purines and 8-hydroxyguanine residues from DNA. Besides glycosylase activity, the is endowed with an EDTA-resistant activity which nicks at apurinic/apyrimidic sites (AP sites). In contrast, DNAs containing chemically reduced AP are not incised by protein. However, strongly inhibited presence synthetic 24 base-pair double-stranded oligonucleotide contains single apurinic site transformed through borohydride reduction into deoxyribose derivative. ability form complex this synthetically modified studied electrophoresis non-denaturing polyacrylamide gels. specifically binds previously sodium borohydride. identified as retardation band on gel electrophoresis. Complex formation reversible apparent dissociation constant, KDapp, 2.6 x 10(-10) M determined. no such obtained between intact or single-stranded either site.