Effect of 2,2'-Dipyridyl on Accumulation of Protoporphyrin IX and Its Derivatives in Yeast Mitochondria and Plasma Membranes

M. G. Strakhovskaya^1*, E. V. Ivanova¹, O. A. Kolesnikova², and G. Ya. Fraikin¹

¹Department of Biophysics, School of Biology, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 939-1115

²Department of Molecular Biology, School of Biology, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 939-4658

^* To whom correspondence should be addressed.

Received June 4, 1998; Revision received June 25, 1998

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The iron chelator 2,2'-dipyridyl (0.2 mM) more than fourfold increased the concentration of protoporphyrin IX and also of its zinc-containing complex in mitochondria of the yeast Saccharomyces cerevisiae. Protoporphyrin IX and a chlorine derivative of protoporphyrin IX which fluoresces at 670-675 nm were found in isolated plasma membranes of the yeast grown in the presence of 0.2 mM 2,2'-dipyridyl. The accumulation of endogenous porphyrins resulted in intensification of lipid photoperoxidation in mitochondria and plasma membranes and in a dramatically increased sensitivity of the cells to visible light (400-600 nm). The relative contribution of photodestruction of subcellular structures to photoinduced cell inactivation is discussed.

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KEY WORDS: protoporphyrin IX, 2,2'-dipyridyl, photosensitized inactivation, lipid photoperoxidation

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