Photolytic cleavage of DNA by nitrobenzamido ligands linked to 9-aminoacridines gives DNA polymerase substrates in a wavelength-dependent reaction

TY - JOUR

T1 - Photolytic cleavage of DNA by nitrobenzamido ligands linked to 9-aminoacridines gives DNA polymerase substrates in a wavelength-dependent reaction

AU - Buchardt, O

AU - Nielsen, Peter E.

PY - 1991/1/1

Y1 - 1991/1/1

N2 - A series of reagents containing 3- or 4-nitrobenzamido ligands tethered to 9-aminoacridine via variable-length linkers have been prepared and their properties as photochemical DNA cleavers (photonucleases) examined. When irradiated with approximately 300-nm light, where the nitrobenzamido ligand can absorb, they cleave DNA in an oxygen-independent reaction presumably involving oxygen transfer from the nitro group to the deoxyribose units of the DNA backbone (Nielsen et al., 1988b). This reaction is pH independent and only slightly affected by the linker length, and the DNA fragments are not substrates for DNA polymerase. When approximately 420-nm light is used, were only the 9-aminoacridinyl ligands absorb, the DNA cleavage is also oxygen-independent but pH dependent, requires DNA saturation with the reagent (base pair:reagent less than or equal to 2), and is most efficient with the longer linkers. The cleavage is specific for guanine residues and results in 5'-phosphate termini and heterogeneous (more than four products) 3'-termini. One of the products is presumably 3'-hydroxy since DNA photocleaved with nitrobenzamido acridine reagents and 420-nm radiation are substrates for DNA polymerase in a nick translation assay as well as for the Klenow fragment. An electron-transfer mechanism is suggested.

AB - A series of reagents containing 3- or 4-nitrobenzamido ligands tethered to 9-aminoacridine via variable-length linkers have been prepared and their properties as photochemical DNA cleavers (photonucleases) examined. When irradiated with approximately 300-nm light, where the nitrobenzamido ligand can absorb, they cleave DNA in an oxygen-independent reaction presumably involving oxygen transfer from the nitro group to the deoxyribose units of the DNA backbone (Nielsen et al., 1988b). This reaction is pH independent and only slightly affected by the linker length, and the DNA fragments are not substrates for DNA polymerase. When approximately 420-nm light is used, were only the 9-aminoacridinyl ligands absorb, the DNA cleavage is also oxygen-independent but pH dependent, requires DNA saturation with the reagent (base pair:reagent less than or equal to 2), and is most efficient with the longer linkers. The cleavage is specific for guanine residues and results in 5'-phosphate termini and heterogeneous (more than four products) 3'-termini. One of the products is presumably 3'-hydroxy since DNA photocleaved with nitrobenzamido acridine reagents and 420-nm radiation are substrates for DNA polymerase in a nick translation assay as well as for the Klenow fragment. An electron-transfer mechanism is suggested.

KW - Aminoacridines/pharmacology

KW - Bacterial Proteins/metabolism

KW - Benzamides/metabolism

KW - DNA/metabolism

KW - DNA Damage

KW - DNA Ligases/metabolism

KW - DNA-Directed DNA Polymerase/metabolism

KW - Escherichia coli/enzymology

KW - Nitro Compounds/metabolism

KW - Phosphorus Radioisotopes

KW - Phosphotransferases/metabolism

KW - Photochemistry

KW - Plasmids

M3 - Journal article

C2 - 1652288

SN - 1043-1802

VL - 2

SP - 57

EP - 66

JO - Bioconjugate Chemistry

JF - Bioconjugate Chemistry

IS - 1

ER -