THE PHOTODEGRADATION OF PORPHYRINS IN CELLS CAN BE USED TO ESTIMATE THE LIFETIME OF SINGLET OXYGEN

Photochemistry and Photobiology - Tập 53 Số 4 - Trang 549-553 - 1991
Johan Moan1, Kristian Berg2
1Institute for Cancer Research, Oslo, Norway
2Institute for Cancer Research, 0310 Montebello, Oslo 3, Norway

Tóm tắt

Abstract—NHIK 3025 cells were incubated with Photofrin II (PII) and/or tetra (3‐hydroxyphenyl)porphyrin (3THPP) and exposed to light at either 400 or 420 nm, i. e. at the wavelengths of the maxima of the fluorescence excitation spectra of the two dyes. The kinetics of the photodegradation of the dyes were studied. When present separately in the cells the two dyes are photodegraded with a similar quantum yield. 3THPP is degraded 3–6 times more efficiently by light quanta absorbed by the fluorescent fraction of 3THPP than by light quanta absorbed by the fluorescent fraction of PII present in the same cells. The distance diffused by the reactive intermediate, supposedly mainly 1O2, causing the photodegradation was estimated to be on the order of 0.01–0.02 μm, which corresponds to a lifetime of 0.01–0.04 μs of the intermediate in the cells. PII has binding sites at proteins in the cells as shown by an energy transfer band in the fluorescence excitation spectrum at 290 nm. During light exposure this band decays faster than the Soret band of PII under the present conditions. Photoproducts (1O2 etc.) generated at one binding site contribute significantly in the destruction of remote binding sites.

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Thông tin xuất bản

Photochemistry and Photobiology

Tập 53 Số 4

549-553

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