DNA binding to crystalline silica characterized by Fourier-transform infrared spectroscopy.
The interaction of DNA with crystalline silica in buffered aqueous solutions at physiologic pH has been investigated by Fourier-transform infrared spectroscopy (FT-IR). In aqueous buffer, significant changes occur in the spectra of DNA and silica upon coincubation, suggesting that a DNA-silica complex forms as silica interacts with DNA. As compared to the spectrum of silica alone, the changes in the FT-IR spectrum of silica in the DNA-silica complex are consistent with an Si-O bond perturbation on the surface of the silica crystal. DNA remains in a B-form conformation in the DNA-silica complex. The most prominent changes in the DNA spectrum occur in the 1225 to 1000 cm-1 region. Upon binding, the PO2- asymmetric stretch at 1225 cm-1 is increased in intensity and slightly shifted to lower frequencies; the PO2- symmetric stretch at 1086 cm-1 is markedly increased in intensity and the band at 1053 cm-1, representing either the phosphodiester or the C-O stretch of DNA backbone, is significantly reduced in intensity. In D2O buffer, the DNA spectrum reveals a marked increase in intensity of the peak at 1086 cm-1 and a progressive decrease in intensity of the peak at 1053 cm-1 when DNA is exposed to increasing concentrations of silica. The carbonyl band at 1688 cm-1 diminishes and shifts to slightly lower frequencies with increasing concentrations of silica. The present study demonstrates that crystalline silica binds to the phosphate-sugar backbone of DNA.(ABSTRACT TRUNCATED AT 250 WORDS)
Mao
Y
Y
Laboratory of Experimental Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-0041.
Daniel
L N
LN
Whittaker
N
N
Saffiotti
U
U
D000818:Animals; D002021:Buffers; D002417:Cattle; D003460:Crystallization; D004247:DNA / Q000378:metabolism*; D017666:Deuterium Oxide; D012822:Silicon Dioxide / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water
D002021:Buffers; D014867:Water; D012822:Silicon Dioxide; D004247:DNA; D017666:Deuterium Oxide