Interaction of psoralen-derivatized oligodeoxyribonucleoside methylphosphonates with single-stranded DNA.
Oligodeoxyribonucleoside methylphosphonates derivatized at the 5' end with 4'-(amino-alkyl)-4,5',8-trimethylpsoralen were prepared. The interaction of these psoralen-derivatized methylphosphonate oligomers with synthetic single-stranded DNAs 35 nucleotides in length was studied. Irradiation of a solution containing the 35-mer and its complementary methylphosphonate oligomer at 365 nm gave a cross-linked duplex produced by cycloaddition between the psoralen pyrone ring of the derivatized methylphosphonate oligomer and a thymine base of the DNA. Photoadduct formation could be reversed by irradiation at 254 nm. The rate and extent of cross-linking were dependent upon the length of the aminoalkyl linker between the trimethylpsoralen group and the 5' end of the methylphosphonate oligomer. Methylphosphonate oligomers derivatized with 4'-[[N-(2-aminoethyl)amino]methyl]- 4,5',8-trimethylpsoralen gave between 70% and 85% cross-linked product when irradiated for 20 min at 4 degrees C. Further irradiation did not increase cross-linking, and preirradiation of the psoralen-derivatized methylphosphonate oligomer at 365 nm reduced or prevented cross-linking. These results suggest that the methylphosphonate oligomers undergo both cross-linking and deactivation reactions when irradiated at 365 nm. The extent of cross-linking increased up to 10 microM oligomer concentration and dramatically decreased at temperatures above the estimated Tm of the methylphosphonate oligomer-DNA duplex. The cross-linking reaction was dependent upon the fidelity of base-pairing interactions between the methylphosphonate oligomers and the single-stranded DNA. Noncomplementary oligomers did not cross-link, and the extent of cross-linking of oligomers containing varying numbers of noncomplementary bases was greatly diminished or eliminated.(ABSTRACT TRUNCATED AT 250 WORDS)
Lee
B L
BL
Division of Biophysics, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Maryland 21205.
Murakami
A
A
Blake
K R
KR
Lin
S B
SB
Miller
P S
PS
D001483:Base Sequence; D004277:DNA, Single-Stranded; D011564:Furocoumarins / Q000138:chemical synthesis; D007202:Indicators and Reagents; D007700:Kinetics; D008027:Light; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis*; D063065:Organophosphonates; D013816:Thermodynamics; D014307:Trioxsalen / Q000031:analogs & derivatives / Q000138:chemical synthesis
D004277:DNA, Single-Stranded; D011564:Furocoumarins; D007202:Indicators and Reagents; D009838:Oligodeoxyribonucleotides; D063065:Organophosphonates; D014307:Trioxsalen