Mechanisms of Photodynamic Damage Induced in Cellular Systems (original) (raw)

Light in Biology and Medicine, 1988

Abstract

Although it is well known that cells do not survive photodynamic treatment with photosensitizers, the actual mechanism of cell death is unknown in most cases and may also be different in different cells. Most cellular systems prove to be sensitive to photodynamic damage, because most constituents of cells, proteins, nucleic acids, lipids and coenzymes can in principle be photooxidized. The actual oxidation depends on many factors such as the intracellular localization of both the photosensitizer and the target molecules. An example is the intralysosomal enzyme β-glucuronidase, which in intact L929 cells is not inactivated at all, but when the cells are disrupted by sonication this enzyme proves to be quite sensitive to photoinactivation by HPD (Boegheim et al., 1987). The mechanism of inactivation of cellular systems has only been clarified in very few cases. Photooxidation of cysteine or histidine residues is often the reason for the inactivation of functional proteins. Examples are the inactivation of the enzymes glyceraldehyde-3-phosphate dehydrogenase and succinate dehydrogenase and the inhibition of some membrane transport systems.

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