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The Origin of115–130°C Thermoluminescence Bands in Chlorophyll‐Containing Material
Author(s) -
Vavilin Dmitrii V.,
Ducruet JeanMarc
Publication year - 1998
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1998.tb02488.x
Subject(s) - thylakoid , chemistry , thermoluminescence , photochemistry , chlorophyll a , algae , analytical chemistry (journal) , chloroplast , luminescence , chromatography , botany , materials science , biochemistry , biology , optoelectronics , gene
High‐temperature thermoluminescence (TL) emitted in the temperature region from +50 to +150°C has been studied in a variety of chlorophyll‐containing samples that were allowed to dry during the TL measurement. Analysis of the recorded traces by a multicomponent‐fit‐ting procedure revealed the existence of up to three bands of nonphotosynthetic origin with peak positions at62–75,114–128 and151–157°C and apparent activation energies of 27.0‐28.8, 14.1‐15.4 and 22.1‐23.3 kcal/mol (the bands are denoted as HT 1 HT 2 and HT 3 , respectively). Low‐temperature treatment of leaves, incubation of algae in the presence of paraquat, exposure of algae or isolated thylakoids to a strong light, all conditions known to stimulate oxidative damage to membrane lipids, caused appearance of a small HT 1 , band and significant rise in the intensity of the HT 2 band. The increase in the HT 2 component correlated positively with accumulation of conjugated dienes and malondialdehyde in thylakoids illuminated with a strong light. Different quenchers of active oxygen species and scavengers of free radicals added to preilluminated thylakoids or thylakoid lipid extracts before the TL measurements, as well as injection of argon into the TL measuring chamber, caused no changes in the intensity of the HT 2 emission. The HT 2 band in the thylakoids increased strongly upon addition of linoleate peroxidized by hydroxyradicals generated in the Fenton reaction but remained unchanged if the linoleate was oxidized with the use of lipoxygenase. We suggest that the HT 2 band arises due to thermal decomposition of lipid cyclic peroxides present in the samples. In turn, the decomposition reaction leads to formation of carbonyls in triplet state with following migration of excitation energy toward chlorophyll. Contrary to the HT 1 , and HT 2 bands, the HT 3 band of TL cannot be associated with the thermolysis of lipid peroxidation products already present in the samples before starting the TL gradient.