Biochemistry, Department of
Date of this Version
1979
Abstract
The absolute photoelectron quantum yield spectra for benzo[ajpyrene and dimethylbenzanthracene are presented in the wavelength range 180-230 nm. These polycyclic aromatic carcinogens have photoelectron quantum yields of approximately 2 X 10-3 electrons per incident photon at 180 nm. The quantum yields fall off quickly and monotonically at wavelengths longer than 210 nm (5.9 eV). Threshold values for benzo[a]pyrene and dimethylbenzanthracene are 5.25 ± 0.06 eV and 5.27 ± 0.04 eV, respectively. The photoelectron quantum yields of benzo[a]pyrene and dimethylben-zanthracene are several orders of magnitude greater than typical components of biological membranes (amino acids, phospholipids, and polysaccharides). Preliminary micrographs of benzo[a]pyrene and dimethylbenzanthracene sublimed onto poly(L-lysine) and onto dimyristoyl phosphatidylcholine demonstrate the high contrast of small crystallites of carcinogens against a background of membrane components. These results and calculations involving relative contrast factors suggest that the distribution of these carcinogens in biological membranes can be determined by using photoelectron microscopy.
Comments
Published in Proc. Natl. Acad. Sci. USA Vol. 76, No. 9, pp. 4180-4184, September 1979. Used by Permission