Laser photochemistry of DNA: Two-photon absorption and optical breakdown using high-intensity, 532-nm radiation

Journal Article · Wed Nov 07 04:00:00 EST 1990 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00179a043· OSTI ID:5678268

Hefetz, Y; Dunn, D A; Deutsch, T F; Buckley, L; Kochevar, I E ^[1]; Hillenkamp, F ^[2]

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1. Harvard Medical School, Boston, MA (United States)
2. Univ. of Muenster (West Germany)

Formation of cyclobutylpyrimidine dimers and strand breaks in double-stranded DNA was investigated by using 532-nm, 28-ps pulses from a frequency-doubled, mode-locked Nd:YAG laser at intensities below and above the threshold for optical breakdown. Two-photon absorption by DNA was detected in the absence of optical breakdown by measuring the yields of cyclobutylpyrimidine dimers formed in supercoiled pBR322 DNA. The yield of cyclobutylpyrimidine dimers per laser pulse was measured at seven peak intensities between 1.03 and 8.04 GW/cm{sup 2}. A plot of the ln (dimer yield/pulse) versus ln (photon flux) was linear with a slope of 1.88 {plus minus} 0.26. The two-photon cross section for absorption at 532 nm was calculated to be 0.5 ({plus minus}0.2) {times}{sup {minus}52} cm{sup 4} s photon{sup {minus}1} per nucleotide. Experiments performed by using intensities above the threshold for optical breakdown caused breaks in the DNA strands but no cyclobutylpyrimidine dimers. The free-radical quencher, mannitol, partially inhibited formation of the strand breaks, indicating that the mechanical processes initiated by the plasma also contribute to the creation of DNA strand breaks.

• OSTI ID: 5678268
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 112:23; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

560400* -- Other Environmental Pollutant Effects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL EFFECTS
BIOSYNTHESIS
CHEMICAL REACTIONS
DATA
DNA
ELECTROMAGNETIC RADIATION
EXPERIMENTAL DATA
GENETIC EFFECTS
INFORMATION
LASER RADIATION
LASER-PRODUCED PLASMA
MODE LOCKING
MULTI-PHOTON PROCESSES
NUCLEIC ACIDS
NUMERICAL DATA
ORGANIC COMPOUNDS
PLASMA
POWER DENSITY
PYRIMIDINE DIMERS
RADIATIONS
RADICALS
SENSITIVITY
STRAND BREAKS
SYNTHESIS